The reader relay PCB is used to process images on a line-by-line basis. Its major functions are as follows:1. Analog image processing• CMOS sensor drive• CMOS sensor output gain correction and offset correction• CMOS sensor output A/D conversion2. Digital image processing• Shading correctionTargetvalueCMOS sensor (1 line)Analog image signalAnalog imageprocessing- Gain correction- Offset correctionA/DconversionCMOS sensordrive controlCMOS sensorcontrol signalGaincorrectiondataDigitalimagesignalIC110Digital imagesignal8Reader relay PCBContact image sensor (CIS)J554RAMShading correctionIC2SerialcommunicationI/F● CMOS Sensor DriveThe CMOS sensor used in this machine is a 1-line linear image sensor consisting of 7488 photocells. After completion ofphotoelectric conversion in the lightreceiving block, the signals are output to the AP circuit in the reader relay PCB in parallel foreach channel (total four channels) of the CMOS sensor array.CMOS sensor 1CMOS sensor 4 CMOS sensor 3HL L HH L HL H H L ………outputLight receiving block● CMOS Sensor Output Gain Correction and Offset CorrectionThe analog video signals output from the CMOS sensor are corrected so that they will have a specific gain level (gain correction),and the output voltages generated in the absence of incident light are also corrected so that they it will have a specific offset level(offset correction).● CMOS Sensor Output A/D ConversionAfter completion of the above corrections, the analog video signals are converted to digital signals corresponding to individualpixel voltage levels by the A/D converter.● Shading Correction (Outline)The CMOS sensor outputs are necessary even for the following reasons even when the density of the original is uniform:(1) Variation in sensitivity among CMOS sensor pixels(2) Variation in light intensity of rod lens arrayThe machine performs shading correction to even out the CMOS sensor output.2. Technical Explanation34
