Rgb Signal Processing Circuit - Toshiba MM20E45 Technical Training Manual

SECTION III RGB SIGNAL PROCESSING CIRCUIT
1. OUTLINE
The signal flow is explained as follows. RGB signal is input
to D-SUB 15P and is processed to be output at CRT Drive
circuit.
2. OPERATION AND FLOW OF RGB
SIGNAL
Fig. 1 shows flow chart of RGB signal.
3. CIRCUIT OPERATION
(1) RGB signal input at D-SUB 15P is supplied to pins 2, 6,
10 of RGB signal processing IC M52327SP respectively.
(2) The signal which is input to RGB signal processing IC,
is processed in four steps ; 1) Amplification, 2) Contrast
control, 3) Brightness control, 4) Black level clamp.
After that, the signal is output at pins 28, 24, 20 and then
is input to pins 1, 2, 3 of Signal switching IC AN5862K.
(3) In TV reception, R-Y, G-Y and B-Y outputs of IC501
(4) TV/RGB switching pulse output from ICX001
ICR02
RGB AMP
M52327SP
Fig. 1
3-1
TA8801AN are selected by IC216 AN5862K and ICR03
AN5862K, and are output at pins 5, 6, 8 of ICR03
AN5862K.
TB1203AP, OSD switching pulse output from
microcomputer and blanking pulse are input to OR gate
circuit. And output from OR gate is input to pin 4 of
ICR03 AN5862K.
These operations function as following 3 items.
In TV mode, output from ICR03 AN5862K is
turned over to TV.
In RGB mode, OSD signal is made by OSD
switching pulse from OR gate.
In RGB mode, blanking is performed.