1 Outline

1-1. Circuit Configuration

The video signal process circuit consists of a video signal demodulation (NTSC, PAL, SECAM), RGB signal (VGA, SVGA) amplification and audio signal amplification circuits. Fig. 7-1 shows the block diagram.

1-2. Video Signal Demodulation Block

The video signal demodulation block demodulates the composite video signal and YC signal into the RGB signals. The composite video signal is separated into a luminance signal (Y) and a color signal (C) in passing through a digital comb filter.

The YC signals selected by the input SW IC are processed in the Video/Color process IC and color difference signal delay circuits, and a Y color difference signal is created. At the same time the Y signal is corrected in its picture sharpness by the sharpness correction circuit and then fed to the RGB demodulation IC. The RGB demodulation IC develops R, G, and B signals.

1-3. RGB Signal Amplification Circuit Block

The RGB input signals are gain-adjusted in passing through the RGB process IC after the signals are switched to the RGB demodulated video signal, and then the RGB input signals are fed to the drive circuit provided in a later stage through the switching circuits.

The sync signal is corresponding to HD, VD, composite sync (CS) and SYNC ON G signals. The sync signal entered is separated into a HD and VD and waveform-shaped in the sync separation IC.

1-4. Audio Signal Amplification Block

Audio signal inputs are corresponding to L and R stereo inputs on the video and RGB inputs. The signals are output to the audio signal output terminals through the input SW IC. At the same time, the L and R signals are mixed, level adjusted in the volume control IC, and amplified by the audio output IC to a sufficient level to drive the speaker.

AVINPUT PC Board AUDIO OUT L

VIDEO OUT O

DIGITAL PC Board

AUDIO PC Board

M5222F

AUDIO OUT

1

HD VD

AVINPUT PC Board AUDIO OUT L

DIGITAL PC Board

AUDIO PC Board

VIDEO OUT O

VIDEO AUDIO L

HD VD

RGB AUDIO L

RGB IN R

CAMERA-Y CAMERA-C

From camera block

RGB AUDIO L

RGB IN R

CAMERA-Y CAMERA-C

From camera block

From Microcomputer

I2C

DAC

CXA1315M

Fig. 7-1 Block diagram

BUFFER

0 0

Post a comment