LG RD-JT30 Service Manual page 133

DDC interface – Providing Digital Display Channel , which include VCC(Pin9) ,
SCL(Pin15) , SDA(Pin12) .
Analog Flat Panel Interface (ADC Converter) , AD9883
The ADC converter digitizes the input analog RGB data signal from D_SUB and output
the digital data streams to Image Processor.The normal voltage level of analog RGB
input signals is about 0.7V , while the ADC digital signal output to Image Processor is
LVTTL level , about 3.3V. The ADC , AD9883 could supports up to pixel rate at about
140MHZ , which is about SXGA 75HZ analog input signal. There are some other
interface signals related to AD9883
SOGIN – Sync On Green input from Image Processor, the signal enable the JT31 support
the very special VGA input signal.
GCOAST – Input signal from Image Processor, the signal enable the JT31 support the
Machintosh analog input format.
GCLK – Output to Image Processor as Pixel Clock, providing the reference clock for
Image Processor.
GHS – Providing the Horizontal Synchronization signal to Image Processor.
GVS - Providing the Vertical Synchronization signal to Image Processor.
GRE, GGE, GBE – Digital data stream to Image Processor which is higher than SXGA
75HZ .
Image Processor (PW166)
The most important IC is the image Processor, here below list its main function.
- Supporting input digital data stream up to UVGA and output digital data up to SXGA.
- Two input port , which are Graphic port ( VGA format ) and Video port (
format ).
- Frame rate conversion , the output frame rate is independent from the input frame rate and
the
need of external memory for frame rate convertion.
- Up and Down scaling of different input resolution, ensure the same output image size .
- Providing Bitmap OSD picture , which if more fancy than normal OSD chip .
- On chip Microprocessor
The Image Processor is a highly integrated circuit, it include MCU, Scaler, Memory, OSD. This
will increase the stability of the system.
There is some control signals list below
DCLK – pixel clock output to DDP1000, provided as a reference clock for DMD driver.
DVS – Vertical synchronization signal output to DDP1000, provided as Vertical reference
signal for DMD driver.
DHS – Horizontal synchronization signal output to DDP1000, provided as Horizontal reference
most important feature of the Image Processor is memory inside , there is no
video decoder
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