Sanyo VAR-G6E, Service Manual

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3. LCD Block
During EE, gamma conversion is carried out for the 10-bit
RGB data which is input from the A/D conversion block of the
CCD to the ASIC in order that the
γ
revised can be displayed
on the video. The YUV of 640 x 480 is then transferred to the
SVRAM.
The data which has accumulated in the SDRAM is converted
to digital YUV signal in conformity to ITUR-601 inside the ASIC
by SDRAM control circuit inside the ASIC, the data is sent to
the LCD driver IC and displayed the image to LCD panel.
If the shutter button is pressed in this condition, the 10-bit
data which is output from the A/D conversion block of the
CCD is sent to the SDRAM (DMA transfer), and is displayed
on the LCD as a freeze-frame image.
During playback, the JPEG image data which has accumu-
lated in the compact flash card is converted to YUV signals.
In the same way as for EE, the data is then sent to the SDRAM,
converted to digital YUV signal in conformity to ITUR-601 in-
side the ASIC, the data is sent to the LCD driver IC and dis-
played the image to LCD panel.
The LCD driver is converted digital YUV signals to RGB sig-
nals from ASIC, and these RGB signals and the control sig-
nal which is output by the LCD driver are used to drive the
LCD panel. The RGB signals are 1H transposed so that no
DC component is present in the LCD element, and the two
horizontal shift register clocks drive the horizontal shift regis-
ters inside the LCD panel so that the 1H/1V transposed RGB
signals are applied to the LCD panel.
Because the LCD closes more as the difference in potential
between the VCOM (common polar voltage: AC drive) and
the R, G and B signals becomes greater, the display becomes
darker; if the difference in potential is smaller, the element
opens and the LCD become brighter. In addition, the bright-
ness and contrast settings for the LCD can be varied by means
of the serial data from the ASIC.