Canon iPF825, Service Manual

Page: 92 / 316

Chapter 2
2-22
2.3.2.3 Carriage Unit
2.3.2.3.1 Functions of Carriage Unit
0020-5488
a) Printhead mounting function
The carriage, which fixes the printhead in position mechanically, is connected to the contacts of the head relay PCB.
b) Control function
The carriage carries a carriage relay PCB, which relays drive signals from the main controller PCB, a head relay PCB, which relays printhead drive signals to the
printhead, a linear encoder, which generates print timing signals, and a multi sensor, which detects the width of paper and skews in it, adjusts is registration and the
head height.
The carriage relay PCB is connected to the main controller PCB by a flexible cable.
c) Carriage drive function
The carriage is moved over the platen by means of the carriage belt that is driven by the power imparted from the carriage motor.
d) Printhead maintenance function
This printer performs cleaning operations, such as wiping the printhead and sucking inks, with the carriage halted at its home position.
e) Nozzle check function
This printer carries out an ink discharge operation with the carriage halted at the head management sensor, locating a non-discharging nozzle in the printhead.
f) Carriage height adjustment function
If the separation between the face of the printhead and the paper (carriage height) is varied as a result of differing paper thicknesses, crooked or curled paper or
other problems, the printer is liable to generate excess mist as the carriage height increases or to result in head rubbing as the carriage height decreases.
To maintain an acceptable carriage height, the lift motor is driven according to the selected paper type, feeding method, print conditions (borderless printing/prior-
itized picture quality) , environmental condition(temperature/humidity) and multi sensor measurements to automatically adjust the separation between the face of
the printhead and the paper
The table below shows the relation between the media type and the height of the head.
T-2-1
g) Paper leading edge detection function/paper width detection function/skew detection function
The multi sensor attached to the lower left part of the carriage detects the leading edge and width of paper feeding on the platen and any skews in it.
h) Automatic printhead position adjustment function
The multi sensor attached to the lower left part of the carriage reads an adjustment pattern printed on a form and adjusts the print timing of each printhead automat-
ically.
i) Remaining roll media detection function
The printer prints a bar code on roll media upon installation of the roll media. The multi sensor attached to the lower left part of the carriage detects the remaining
roll length.
j) Internal unit temperature sensor
A thermistor installed on the head relay PCB detects the internal unit temperature near the printhead.
Height of printhead
(mm)
Media type Remarks
1.3 (Lowest) Photopaper, Synthetic paper, Film, Plain paper(Line drawing) Capping position
1.8 (Low) Coated paper(Line drawing)
2.0 (Standard) Plain paper, Coated paper, Fabric banner
2.2 (High) Premium matte paper, Fine art(watercolor,block print)
2.6 (Highest) Canvas