Xerox WorkCentre XK50cx Service Manual

Also see for WorkCentre XK50cx: User guide

4-11CircuitIMAGE PROCESSING(1) Image signal input: CCD output signals are offsetat 0.7V with about 2V white level. Optimum inputlevel of DUOIP2 is 0.7V offset and 2V whitelevel. So OP AMP is used to designinterface circuit of DUOIP2.(2) Image processing : The scanner reads pixel datavalue of image sensor CCD Charge CoupledDevice 600dpi lines by 600dpi lines. For monocopy mode, two kinds of algorithms are used.One is TIP algorithm for Fast copy and normal,the other is Error diffusion algorithm for Bestcopy.For color copy mode, Samsung color halftoningalgorithm is used for all modes. The colorcorrection and conversion into CMY print dataare certainly processed for improving imageguality.The external SRAM (1Mbit, 15ns) is used foronly color halftoning process, and the otherprocessing parameters are handled usinginternal SRAM. Also another external SRAM(1Mbit-15ns)is used for LGC (Line gapcorrection) of CCD Module.KEY FEATURES(1) Target Product : Color Fax/Inkjet Digital ColorCopier.(2) Packeg & Technology : 0.35μ CMOS Process(TLM), 208 QFP, STD90 Library.(3) Maximum Action Frequency : 40Mhz(4) Contain ON-CHIP OSCILLATOR.(5) Only assist Rester Scanning Method.(6) Image Sensor : 300/600dpi color CIS & CCD.(7) A/D Converter : 12bits pipelined half-flash typecontain.(8) Support Various Type of Scanning .1) COLOR GRAY IMAGE : each 8 bits / RGB2) MONO GRAY IMAGE : 8 bits / pixel3) COLOR BINARY IMAGE : 3 or 4 or 6 bits/ pixel (for CMY/CMYK/PHOTO)4) MONO BINARY IMAGE : 1 bits / pixel(for TEXT/PHOTO)(9) Maximum Scanning With : A4, 600dpi(maximum 5K available by line)(10) Minimum Pixel Processing Time : 11 systemclock (275nsec)(11) Ideal MSLT (A4, 600dpi Standard)1) COLOR GRAY IMAGE : 3 X 5K X 275nsec=4.125msec (2 CPM)2) MONO GRAY IMAGE : 1 X 5K X 275nsec=1.375msec (6 CPM)3) COLOR BINARY IMAGE : 3 X 5K X 275nsec=4.125msec (2 CPM)4) MONO BINARY IMAGE : 1 X 5K X 275nsec=1.375msec (6 CPM)(12) Support Smart Media I/F- For ECC, when the Host read/write the SmartMedia by page, automatically generating the3 byte of parity information on the page.(13) Contain Step Motor Controller- Using IRQ, updating notor pattern and intervalas S/W.- Motor pattern and interval pass by doublebuffering structure.- Possible to activating and motivating theImage Sensor.(14) Support Memory Copy Function- Using DMA RX, printing image saved onsystem data memory.(15) For the various CCD I/F, support maximum,5 lines of LGC function.(16) Contain SRAM BIST(Built-In Self Test) Logic.IMAGE PROCESSING PART(1) LAT(Local Adaptive Thresholding) for TEXTdocument.- Use 5 X 5 LOCAL WINDOW- ABC(Automatic Background Control) function(Tmin automatic change)(2) Mixed mode processing for PHOTO or TEXT/PHOTO mixed document.- (MONO/COLOR) IMAGE ENHANCEMENT→MODIFIED ERROR DIFFUSING.- Serching the edge using directing edgealgorithm as considered the visualcharacteristic of human then emphasize andapply the MODIFIED ERROR DIFFUSIONMETHOD.(3) Color Halftoning- MODIFIED ERROR DIFFUSION METHOD.(Removing the worm artifact phenomenon whichis problem of existing errer diffusing method andpreventing the overlaping color of cyan andmegenta in the bright scene.)- Normal copy : color ink(CMY) + black ink(K)→ 3color (CMY) or 4color (CMYK)- Photo copy : color ink(CMY) + photo ink(KLcLm)→ 6color (CMYKLcLm)