Sanyo VPC-S60 Service Manual

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Contents

– 5 –1-2. CP1 CIRCUIT DESCRIPTION1. Circuit Description1-1. Digital clampThe optical black section of the CCD extracts averaged val-ues from the subsequent data to make the black level of theCCD output data uniform for each line. The optical black sec-tion of the CCD averaged value for each line is taken as thesum of the value for the previous line multiplied by the coeffi-cient k and the value for the current line multiplied by thecoefficient (k-1).1-2. Signal processor1. γ correction circuitThis circuit performs (gamma) correction in order to maintaina linear relationship between the light input to the cameraand the light output from the picture screen.2. Color generation circuitThis circuit converts the CCD data into RGB signals.3. Matrix circuitThis circuit generates the Y signals, R-Y signals and B-Y sig-nals from the RGB signals.4. Horizontal and vertical aperture circuitThis circuit is used gemerate the aperture signal.1-3. AE/AWB and AF computing circuitThe AE/AWB carries out computation based on a 256-seg-ment screen, and the AF carries out computations based ona 11-segment screen.1-4. SDRAM controllerThis circuit outputs address, RAS, CAS and AS data for con-trolling the SDRAM. It also refreshes the SDRAM.1-5. Communication control1. SIOThis is the interface for the 8-bit microprocessor.2. PIO/PWM/SIO for LCD8-bit parallel input and output makes it possible to switch be-tween individual input/output and PWM input/output. It is pre-pared for 16-bit parallel output.1-6. TG/SGTiming generated for 6 million pixel CCD control.1-7. Digital encorderIt generates chroma signal from color difference signal.1-8. JPEG encorder and decorderIt is compressed and elongated the data by JPEG system.2. Outline of OperationWhen the shutter opens, the serial signals (“take a picture”commands) from the 8-bit microprocessor is input to ASIC(IC101) and operation starts. When the TG/SG drives the CCD,picture data passes through the A/D and CDS, and is theninput to the ASIC as 12-bit data. The AF, AE, AWB, shutter,and AGC value are computed from this data, and three expo-sures are made to obtain the optimum picture. The data whichhas already been stored in the SDRAM is read by the CPUand color generation is carried out. Each pixel is interpolatedfrom the surrounding data as being either R, G and B primarycolor data to produce R, G and B data. At this time, correctionof the lens distortion which is a characteristic of wide-anglelenses is carried out. After AWB and γ processing are carriedout, a matrix is generated and aperture correction is carriedout for the Y signal, and the data is then compressed by theJPEG method by (JPEG) and is then written to card memory(SD card).When the data is to be output to an external device, it is takendata from the memory and output via the USB. When playedback on the LCD and monitor, data is transferred from memeryto the SDRAM, and the data elongated by JPEG decorder isdisplayed over the SDRAM display area.3. LCD BlockThe LCD display circuit is located on the CP1 board, andconsists of components such as a power circuit and VCOMcontrol circuit.The signals from the ASIC are 8-bit digital signals, that isinput to the LCD directly. The 8-bit digital signals are con-verted to RGB signals inside the LCD driver circuit . LCD isinput signals from ASIC directly to the LCD, and function suchas image quality are controlled.Because the LCD closes more as the difference in potentialbetween the VCOM (common polar voltage: AC) and the R,G and B signals becomes greater, the display becomes darker;if the difference in potential is smaller, the element opens andthe LCD become brighter.In addition, the timing pulses for signals other than the videosignals are also input from the ASIC directory to the LCD.