Hitachi 46W500 Training page 71

DP-3X DIGITAL CONVERGENCE INTERFACE CIRCUIT EXPLANATION
See Digital Convergence Interconnection Circuit Diagram for details.
The Digital Convergence circuit is responsible for maintaining proper convergence of all three colors being pro-
duced by the CRTs. Many different abnormalities can be quickly corrected by running Magic Focus.
The Digital convergence Interconnect Diagram depicts how the Digital Convergence Circuit is interfaced with
the rest of the Projection's circuits. The main components and/or circuits are;
•
THE DIGITAL CONVERGENCE UNIT (called DCU)
•
CONVERGENCE OUTPUT TO STKs
•
CONVERGENCE YOKES
•
MAGIC FOCUS SENSORS AND INTERFACE
•
MAGIC FOCUS activation by Magic Focus Switch on Front Control Panel or customer's Menu.
•
MICROPROCESSOR
•
RAINFOREST IC (Video Processor).
•
SERVICE ONLY SWITCH
•
INFRARED REMOTE RECEIVER
•
ON SCREEN DISPLAY PATH
THE DIGITAL CONVERGENCE UNIT (DCU) (8 Sensor array).
The DCU is the heart of the Digital convergence circuit. Held within are all the necessary components for gener-
ating the necessary waveforms for correction, and associated memories for the adjustment data and Magic Focus
Data.
Adjust through observation
Remote
Control
Infra-Red Decoder
To Video Circuits
Via O.S.D.
Displays CrossHatch
256 Adjusted One Chip CPU
Points
Per/Color
8 bit
128 Kbit
117 Points Per/Color
SLOW
Addressable
EEPROM
by
(2Kbit)
Technician
Also available;
35 Adjustment Points
9 Adjustment Points
117 Points Per/Color
The Block above shows the relationship of the DCU to the rest of the set. Note that the light being produced by
the CRTs is what is used by the sensors for Magic Focus. This allows the DCU to make adjustments regardless of
circuit or mechanical changes or magnet influence, by actually using the light on the screen to make judgments.
EEPROM AND SRAM SHOWN IN FIGURE 1: (8 Sensor Array).
Each color can be adjusted in any one of 117 different locations. The internal workings of the DCU can actually
make 256 adjustment points per color. These adjustment points are actual digital data stored in memory. This
Technician's Eye
Stored during Initialize
Stored Light Sensor Data
EEPROM Timing
2K Bit Controller
Data Comparator
Serial-Parallel
between stored data
Converter
and light sensor data
Error Data
Digital Cross
Timing
Hatch Gen.
Controler
Serial/Parallel
Converter
Gate Array 4000 gates
S-RAM
(256Kbit)
FAST
D/A Conv.
Static Centering
AC Applied, Copy from EEPROM, then caculations will be made. Time, approx. 20 sec.
Sensors (X8)
SCREEN
A/D
Sensor PWB
D/A
X1 X6 X6
Calculation of other 139 points per/color
INTERPOLATION
Back Up
Light
H
R
G
V
B
CRT
CY CLAMP
X6 X6
DIGITAL
CONVERGENCE
CIRCUIT
Figure 1
(Continued on page 2)
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