Panasonic TC-L42D30, Technical Manual

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The main function of the A board is to select and process one of the incoming video signals. All analog video
inputs, including Composite Video, Component Video, PC, and the composite video output of the tuner are
all connected to a video switch for selection and output to IC8000 for further selection. Digital output signal of
the tuner, LAN, HDMI inputs 1 and 2, JPEG data from the SD card slot and USB inputs are connected to
IC8000 for selection. HDMI 2 and 4 enter a HDMI switch for selection and output to IC8000 for further
selection. The video input signals enter IC8000 in their original formats.
All analog signals that enter IC8000 undergo digital to analog conversion. When the signal source signal is
composite, a comb filter separates the video signal into Y and C (luminance and chrominance) signals. S-
Video, which is already Y/C separated, simply passes through the comb filter. The signal is then converted
to RGB data.
At the completion of this process, the format of the composite or S-Video signal is now the same as a digital
480i component signal. If the incoming video is in the 480p, 720P, 1080i,or 1080p format, the Y, Pb, and Pr
signals undergo A/D (analog to digital) conversion only.
Digital television reception of the tuner is output in the form of an IF (Intermediate Frequency) signal, also
known as the transport stream. The transport stream from the tuner enters the VSB I/F (Interface) section of
IC8000 where the video signal is extracted and converted to digital RGB. The JPEG data of the SD card,
HDMI, USB, LAN inputs of IC8000 are also converted into RGB data. The video input interface of IC8000
outputs the selected picture data to the video process circuit.
The Video Process section of the IC performs all picture control operations such as brightness, contrast,
color, tint, etc. On Screen Display data such as channel numbers, Digital TV closed caption, and picture
adjustments are mixed with the video data. The RGB data is then converted to dual 12 bit LVDS (Low
Voltage Differential Signaling) and output to the LCD panel.
IC8000 handles all video applications. It serves as the controller that monitors all operations of the TV.
Signal Process Circuit Explanation