استخدام دارة التكامل في فصل النبضات الرأسية .. كتاب التلفزيون الملون والعادي

The use of the integration circuit in the separation of vertical pulses:

Its work depends on preventing the effect of the horizontal pulses, which leads to the separation of the vertical synchronization pulses - it is a pass circuit for low frequencies only, and it also consists of a circuit
The RC capacitor and resistance have a long time constant, as in Figure (13-14), which is similar to the differential circuit, but the position of the capacitor and resistance is opposite, and we get the output of the circuit from both ends of the capacitor.

Since the time constant of this circuit is long, this means that charging and discharging the capacitor requires a long time, and therefore the capacitor is charged to a very small value and then discharged when the horizontal pulses pass, because its time is very short in relation to the time constant of the integration circuit, and this is what makes the vertical oscillator not affected by the horizontal pulses Figure (15-13) shows the output pulses of the circuit, where the dotted line is the voltage level that influences and controls the vertical oscillator.

equalizer pulses:

The equalizer pulses that we have already mentioned - consist of five equalizer pulses that precede each vertical pulse and five that lag after it, and the width of each of them is half the width of the horizontal synchronization pulse, that is, it is repeated every half line, and these pulses that perform the process of accurate synchronization of the odd and even fields, where it begins The odd field is from and ends in the middle of the last odd line, while the even field starts from the middle of the top of the screen, and ends at the end of the last even line - The equalization pulses charge and discharge the capacitor in the integration circuit with half the value they charge at the horizontal synchronization pulses, because they last half of its time Thus, the vertical synchronization pulse starts from the potential difference, whether it comes after an odd or even field. That is, whether the scan line ends at the end or middle of the screen. As for the wide vertical synchronization pulse, whose time is two or three times more than the time constant of the integration circuit, it charges the capacitor to a high voltage that exceeds the voltage v1 a lot, and this affects the vertical oscillator and adjusts its frequency with the transmission frequency.

note :

It is worth mentioning that every TV picture consists of two interlocking fields, as we explained in detail in a previous chapter.

In many devices, we use a triple integration circuit in the form of a printed circuit that has more efficiency than the single-section circuit