Scan Modes - Canon BJC-3000 Service Manual

BJC-3000
6) Scanner Controller
The scanner controller is an IC that processes the analog signals into digital images.
a) Sensor Control
The sensor control controls the LED and the CCD.
b) Amplifier
The amplifier amplifies the analog input from the CDD.
c) Analog Signal Control
This unit performs offset correction for the amplified analog input, black-level
correction which sets the maximum value to black, etc. on. It also provides the
standard power to the A/D converter.
d) A/D Converter
The A/D Converter converts the analog input, corrected, in the analog signal
control unit to digital 10-bit image data.
e) Image Processing
Image processing unit executes shading correction (variation in image density
between each line in the feeding direction of paper may occur due to the variation
of the sensitivities of the CCD sensor elements and the uneven distribution of light
transmitted through the center and the periphery of the lenses; the scanned data is
compared against a calibration data based on the white calibration sheet to even
out and the density is corrected). It also converts the 10-bit data transmitted from
the A/D converter to 8-bit (256-gradation) data, converts the output resolution,
and carries out the edge emphasis function. It has a 1-bit (2-gradation) image
procession function and built-in SRAM used for output buffer memory.
f) I/F Controller
The I/F controller controls the serial interface between the scanner cartridge in the
carriage and the printer unit. Two types of transfer clock, 4MHz and 2MHz, are
supported for the data transfer between the scanner and the printer.

1.5.2 Scan modes

Scanning
resolution
(H V)
720 720
360 360
300 360
200 180
180 180
90 90
*: Two-pass scanning is performed by feeding a paper for half the pixel width of the
scanning image. The scanning resolution is improved by scanning the same line
twice to balance out the image.
When scanning at 720
adjusted, depending on the paper width, for the direction of the carriage. The longer
the paper width direction, the smaller the scanning pixel width.
TABLE 5-3 SCAN MODES
Scanning Image Pixel Width
Color Black & White
Color (8bit) Gray Scale (8bit)
96*, 128*,160* 256*
256* 256*
256* 256*
256* 256*
256* 256*
256* 256*
720dpi, the scanning image pixel width is automatically
5-13
Carriage Transfer Clock
Speed
Mono (1bit) (inch/sec)
256 Approx. 4.1
256 Approx. 10.0
256 Approx. 10.0
256 Approx. 16.6
256 Approx. 20.0
256 Approx. 28.0
Part 5: Appendix
from Scanner
to Printer
4 MHz
4 MHz
4 MHz
2 MHz
2 MHz
2 MHz