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zTMG-S (timing sensor): verifies that paper is moving through the paper path.zSKR-S (back skew sensor)zSKF-S (front skew sensor)NoteThe ADF has a document detection sensor that detects the presence of paper. This sensor is not shown in the graphic below. When the sensor detects the presence of paper, the LED on the ADF illuminates.Figure 49. ADF feeder sensors
136Chapter 5 Theory of operationENWWADF document skew detection 1One of the skew sensors is activated.2A signal is sent to the SCB.3The SCB begins to read a certain number of clock pulses in 6 mm (.02 inch).4A skew jam is not reported if the second skew sensor is activated before the allotted number of pulses.NoteSkew detection is only performed when the document width is less than or equal to 257 mm (10.1 inches).Figure 50. Document skew jam
ENWWScanned data flow 137Scanned data flowThe MFP has a scan engine with 600 by 600 ppi (pixels per inch) resolution. It has three channels (red, blue, and green) with 10 bits per channel, resulting in the equivalent of a 30-bit scan engine.Analog data is captured by the CCD driver circuit and converted to digital data on the analog processor board. Digital data is then sent through the three channels to the CP. The CP coverts the digital data into one of the three final output types:zHRB (hardware ready bits): most copy jobs are processed at the CP and sent to the print engine as HRB.zPCL-XL: if rotation, book copying, or n-up is chosen in the job, the CP passes PCL-XL data to the print engine and the formatter finishes the processing.zJPEG (lossless): compresses image data from the CP to the formatter when processing a digital send job. The formatter then processes the data into the desired file type (TIFF, MTIFF, JPEG, or PDF).Figure 51. Scanned data flow
138Chapter 5 Theory of operationENWWCopy processorThe copy processor (CP) is the link between the formatter in the print engine and the SCB in the scan engine. Control signals from the formatter are sent to the CP. The CP sends these control signals to the SCB. After the scanning process is completed by the SCB, the scanned data is sent to the CP. The CP processes the image and sends the image data to the formatter.Figure 52. Example of a copy processor (HP LJ 9000mfp/9000Lmfp shown)
ENWWCopy processor 139Scanning process control signalsThe CP controls the following scanning process control signals:zADF unit and flatbed unit operation directs the SCB about the following:•when to scan•how to scan•when to activate motors•when to turn the scanning lamps on and offzImage processing•color alignment•resolution conversion•image sharpening•moire removal•image scaling•shifting of data strips (reconstructing separately processed image data before CP communication to the formatter)•RGB conversion for CP communication•CP communication to the formatter using one of the following formats:•HRB (fastpath) communication with the hard drive on the formatter•PCL-XL (n-up, rotation, book mode) communication with the hard drive on the formatter•