Sony Jumbotron JME-UA200, Service Manual

Page: 32 / 56

4-2(E) JME-UA200
4-3. UNIT CONTROL MODE
Same as in ADJUST mode, the unit control commands are
inserted in the control data blocks and transmitted to the
unit. In making inquiry for model name or brightness
correc-tion value to the unit, if the control data are
transmitted, the inquired data are returned from the unit in
the ASCII codes of serial data at 4800bps for JTU-35/17
Series, or 9600pbs for LDU-15 Series. These data are
received with the line driver (IC35), and entered to the
RXD0 of the MPU (IC40). These data are analyzed and
displayed on the LCD.
4-4. DEMO MODE
Storing video data for demonstration can display pictures
and character patterns of maximum 64x64 dots.
4-5. AUTOMATIC BRIGHTNESS
ADJUSTMENT BY SENSOR
1. Brightness adjustment of reference cell
Photodiode sensor (JME-US15L) detects the brightness of
each element in the Jumbo Tron unit cell, and flows the
current according to the brightness. This current value is
converted into the voltage, and entered through filter
amplifier to the A/D converter of the MPU (IC40) every R,
G and B signals. Here, they are converted into 10bit data.
2. Brightness adjustment
The brightness of each element in the cell to be adjusted is
entered and compared with the reference value. If it is
larger than reference value, the code to reduce the bright-
ness, or if smaller, the code to increase the brightness is
inserted in the control blocks mentioned previously and
transmitted to the unit. Here, again the brightness is
measured and this operation is repeated until the measured
value is equal to the reference value.