Canon iR2318 series, Руководство по обслуживанию, Страница: 119 / 308

Chapter 4
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The flow of analog image processing performed by the contact image sensor (CIS) is as follows:
The light reflected by the original is collected by the rod lens array.
- The light is received by the CMOS sensor array.
- The CMOS sensor array converts the received light to an electric signal and outputs it.
The CMOS sensor array consists of four channels (units).
Each channel is provided with an output correction table to output an image signal after performing gain correction for the input brightness signal.
F-4-15
- After replacing the contact image sensor (CIS), go through the following steps to perform inter-channel output correction:
1) Enter the service mode.
Sequentially press the Additional Functions, # key on the operation panel.
2) Using the upper/lower arrow keys on the operation panel, select "Test".
3) Press the OK key.
4) Using the upper/lower arrow keys on the operation panel, select "Scanner test".
5) Press the OK key.
6) Using the upper/lower arrow keys on the operation panel, select "CS Output Test".
7) Press the OK key.
8) Select "Yes" and then press the OK key.
After completion of the above steps, contact sensor output correction will be performed and parameters will be set automatically.
4.3.3 Enlargement/Reduction
4.3.3.1 Magnification Change in Vertical Scan Direction
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In the Book mode or when the ADF is used
In the vertical scan direction, the image is read at 100%. Magnification is changed by processing data on the image processor PCB.
4.3.3.2 Magnification Change in Horizontal Scan Direction
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Magnification in the sub scanning direction is varied according to the rate of magnification as follows:
1) When magnification is varied to 25% through 49% for reduction
a. In the Book mode
Data is processed using the reader controller PCB and image processor PCB with the document scanning speed held at 118mm/sec.
b. When the ADF is used
The document feed speed (when the ADF is used) is varied between 118 mm/sec and 59 mm/sec according to the rate of magnification, and data is processed using
the reader controller PCB and image processor PCB.
2) When magnification is varied to 50% through 99% for reduction
a. In the Book mode
Data is processed using the reader controller PCB and image processor PCB with the document scanning speed held at 118mm/sec.
b. When the ADF is used
The document feed speed (when the ADF is used) is varied between 118 mm/sec and 236 mm/sec according to the rate of magnification. The reader controller PCB
and image processor PCB are not used for data processing.
3) When magnification is varied to 100% through 200% for enlargement
The document scanning speed (in the BOOK mode) and the document feed speed (when the ADF is used) are varied between 118 mm/sec and 59 mm/sec according
to the rate or magnification. The image processor PCB is not used for data processing.
4) When magnification is varied to 201% through 400% for enlargement
Data is processed using the reader controller PCB and image processor PCB with the document scanning speed held at 59mm/sec.
4.3.4 Detecting the Size of Originals
4.3.4.1 Outline
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The original size is identified by the combination of presence and absence of output levels of the reflection type sensors as summarized in the tables below.
- Absence of paper: The light reflected from the reflection type sensor changes when the copyboard cover is open/close.
- Presence of paper: The light reflected from the reflection type sensor does not change when the copyboard cover is open/close.
This machine is provided with the following sensors. Locations of the sensors are shown below.
- Vertical scan direction: Reflection type photo sensors (2 locations for AB; 1 location for Inch)
Dr
iver circuit
4
CCD channel x 4
3
2
1
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7488 pix
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