Canon BJC 50 Service Manual - Page 134

Part 4: Technical Reference BJC-50 6. SCANNER CARTRIDGE 6.1 Scanner Cartridge Overview The scanner cartridge is a replaceable scanner unit that carries a one-line 128 pixel BASIS. The scanner separates each of the three RGB primary colors of the LED by scanning the same line three times. The color image is output by 8-bit signals, 256 gradation in each RGB primary color. For a monochrome image, the image is lit with a green LED and scanned once to output either a 8-bit or 2-bit signal. The maximum scanning resolution is 360 dpi × 360 dpi. The light source LED within the scanner lights up and illuminates the document on the platen. The light rays hit the image and using an imaging lens the reflected light rays are converged onto the BASIS. The converged light rays are converted to analog signals by the BASIS. After the analog signals have been converted to digital signals by the scanner controller, the scanned image is processed and the image data is sent to the computer via the printer's Centronics interface. Light Emitting Section Light Receving Section M A D E IN JA PA N Signal Contact Figure 4-32 Scanner Cartridge 6.1.1 Block diagram Printer Scanner Cartridge Scanner Controller Interface Control Image Processing +24V dc +5V dc A/D Converter (10 Bit) Analog Signal Control Sensor Control BASIS (Image Sensor) LED (R, G, B) Scanning Documents Figure 4-33 Block Diagram 4-46