Canon BJC-55 Series, Service Manual

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6.2 Scanner Cartridge Structure
1) LED
Red, green and blue LEDs are used to illuminate the scanning document. To
Compensate for the low intensity of the red and green LED's, two red and green LEDs
have been incorporated and a total of five LEDs are mounted on the scanner. Only
the green LED is used for monochrome scanning.
2) Illumination lens
This "D" shaped lens converges the light from the LED light source.
3) Diffusion board
The light intensity of the LED is brighter at the center than at the ends. The diffusion
board allows even distribution of light onto the document.
4) Field lens
This lens prevents any magnification reduction caused by paper gaps when scanning
a lifted or bent document.
5) Imaging lens
This lens is used for forming an image of the light rays converged by the field lens
onto the BASIS.
6) Shading board
The shading board with a slit at the front surface of the BASIS is used to prevent
crosstalk generated in areas adjacent to high contrast areas.
7) BASIS
The scanner cartridge uses a semiconductor type, one-line 128 pixel BASIS (Base-
Stored Image Sensor). Depending on the light amount of the image formed on the
BASIS, electric voltage signals are sent to the scanner controller as image signals.
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BJC-50
Part 4: Technical Reference
2
Scanning Document
BASIS
Mirror
Field Lens
LED
Platen
Slit
PCB
Imaging Lens
LEDs
Field Lens
Mirror
Illumination Lens
Illumination Lens
BASIS
Diffusion Board
Diffusion Board
Imaging Lens
Figure 4-34 Scanner Cartridge