Canon iR4570 Series, Service Manual

Page: 183 / 876

Chapter 5
5-15
To vary the magnification in sub scanning direction, the machine operates as follows depending on the selected
method of reading the original and the selected rate of magnification:
1. In Book Mode
To suit the selected rate of magnification, the speed at which the original is read is varied and the data is processed
by the reader controller PCB/main controller PCB.
EX: for reduction to 25%, the original is read at 236 mm/sec and the data is varied for 50% reduction by the reader
controller PCB (skipping data for 1/2) and for 50% reduction by the main controller PCB (skipping data for 1/2).
EX: at 100%, the original is read at a speed of 236 mm/sec.
T-5-5
2. In ADF Mode
To suit the selected rate of magnification, the speed at which the original is read is varied and the data is processed
by the reader controller PCB/main controller PCB.
EX: for reduction to 25%, the original is read at 236 mm/sec, and the data is processed for 50% reduction (skipping
for 1/2) by the reader controller PCB and for 50% (skipping for 1/2) by the main controller PCB.
EX: for enlargement to 400%, the original is read at a speed of 118 mm/sec, and the data is processed for 200%
enlargement (doubling) by the main control PCB.
T-5-6
Operation
Magnification
25% to
49%
50% to 99% 100% to 400%
Varying the speed of reading the
original (mm/sec)
236 to 120 236 to 119 236 to 59
Processing the data (digital; %) by
the reader controller PCB
50 50 100
Processing the data (digital; %) by
the main controller PCB
50 100 100
Operation
Magnification
25% to
42%
43% to
84%
85% to
170%
171% to
400%
Varying the speed at which the
original is read (mm/sec)
236 to 168
274 to
140
277 to
139
276 to 118
Processing the data (digital; %) by
the reader controller PCB
50 50 100 100
Processing the data (digital; %) by
the main controller PCB
50 100 100 200