التطابق الحركي الراسي .. كتاب التلفزيون الملون والعادي

15-6 Vertical kinematic matching:

The inline color screen valves do not need the process of matching or vertical convergence, and we have dealt with that in a previous chapter. Also, the screen valve may not require any matching process after leaving the factory. While the color screen valve with triggers (Delta) - for the process of vertical motor convergence - as well as for the static convergence of the three rays, and this is what we will explain.

static match:

The matching or convergence of the three rays in the center of the screen (Delta type) is not difficult - it is done by means of permanent magnets installed on the back side of the deflection coils and it is called the process of static matching.

Vertical alignment:

When the rays deviate to the edges of the screen, the matching of these rays is disturbed and they lose their gathering in one place according to Figure (12-15), and this is what happens as a result of the lack of curvature of the screen and the shadow mask in a spherical shape. To correct this imbalance, a matching current is generated and applied to the three matching coils distributed over 120% and placed adjacent to the deviation coils.

Each file is allocated to one of the three colors and consists of two sections of files, one for correcting the vertical match, and the other for correcting the horizontal match, and both sections are on the same core. Figure (13-15) shows that there is no vertical match between the top and bottom screens. The rectification current required for vertical motion matching must have a parabolic wave. This wave is generated from three separate signals taken from the vertical output circuit. One of these signals is connected to the matching circuit, and the remaining two signals have a difference of 180 degrees from the saw wave generated through special coils in the vertical output transformer (VOT). Figure (15-14) This parabolic wave applies a left or right signal from the saw to produce the appropriately shaped parabolic wave. The amount of tilt or deviation depends on the breadth of the saw.

15-7 Vertical eraser circuit:

At the end of scanning each of the two fields of the image, the vertical deviation circuit returns the electronic beam to the top, and during the return period, several horizontal lines scan the screen, and to prevent their appearance on the screen, the vertical output circuit generates erasing or extinguishing pulses. These pulses are applied to the cathode of the screen valve, or to the grid that controls it, and thus extinguishes this beam until it reaches the top of the screen, and in the right place to start, the second field is scanned - and the polarity of the viscous pulses is positive if it is applied to the cathode of the screen valve. It is negative if it is applied to the governing network.

Figure (15-15) shows a circuit with negative polarity. It has a sawtooth pulse. Taken from the vertical deviation files circuit.
However, it cannot be applied directly to the control network because it carries a sawtooth wave component, which can cast shadows on the linear structure of the image (raster) and is therefore passed on a differential circuit C2 and 1R. As shown in the figure, thus only the narrow negative pulse remains to be applied now to the control grid of the screen valve.
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