Caple C702G Wartungshandbuch PDF herunterladen (Seite 132)

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2. DEFLECTION CIRCUIT

2-1. The oscillation and deflection control integrated circuit

The oscillation and the deflection circuit is generated by IC501. IC501 has digital signal processor (DSP)

and generates variety of correction signals by calculations. The feature of IC501 are low tolerance and low

drift of temperature compared with current analog circuit. The functions of IC501 are Horizontal oscillation,

Vertical oscillation, Horizontal position control, Distortion correction, Dynamic focus control, Moire canceler,

and Convergence correction. These correction signals generated by DSP are converted to analog signal by

the D/A converter, and these signals are output from IC output terminal.

1) Digital Signal Processor (DSP)

The digital signal processor generates variety of correction signals by calculations based on MPU (IC801)

data. The DSP generate saw wave by MPU data. The signal, after the AGC in this saw wave, is moved to

the reference signal. This reference signal generates various correction signals. All the signal wave shape

formation inside DSP are done by the operation. The output signals from DSP are converted to analog

signal by the D/A converter, and then these signals are output from IC output terminal.

MPU

DSP

DATA

Reference

signal

AGC

Vertical saw wave

Distortion correction wave

Moire cancel wave

Dynamic focus wave

Convergence correction wave

D/A

converter

IC501

V.sync

(Fig. 2.1) Digital Signal Processor (DSP)

2) 1bit D/A converter (1bit DAC)

Most of the signals which are generated by DSP are output from 1 bit D/A converter. The 1bit D/A

converter is pulse width modulation (PWM) circuit which is operated with 25MHz internal clock signal. The

3.3Vp-p signal which is modulated by pulse width is output from the 1bit D/A converter output terminal.

This signal is integrated by integration circuit which is composed of resistor and capacitor and creates

vertical periodic wave. The vertical dynamic focus control, distortion correction, convergence correction

and moire canceler signals are output from the 1bit D/A converter.

1bit D/A OUTPUT

Integration circuit

Operated by 25MHz clock.

3.3Vp-p

(Fig. 2.2) 1bit D/A converter

1 2 ... 127 128 129 130 131 132 133 134 135 136 137 ... 285 286

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