عملية تركيز الشعاع (Focus) ٢-a .. كتاب التلفزيون الملون والعادي

Figure (11-36) - and it requires the presence of an additional deflection current called the kinetic matching current and it passes in the group of three coils corresponding to the internal magnetic poles as shown in the static convergence - these coils are double and have 120 between them and are separated from each other by magnetic barriers so that only the beam is affected with its assigned magnetic field.

The upper coil affects the blue ray and can correct its trajectory vertically, i.e. up and down - and horizontally. The other two coils are for the red and green stimulating ray, and each ray can also be corrected. And the kinetic mismatch makes the image as if it has three linear structures that do not match the colors with the image, as in Figure (11-37).

Conformance correction current: It feeds the conformity correction coils, and it is a current that changes momentarily with the movement of the beam and has a parabolic change, as in Figure (11-35).

The need for kinetic matching efforts to match the three rays at the edges of the screen, given that they are not completely spherical.

This current comes from the horizontal and vertical deviation circuit, which includes many correction adjustments. Each of them has its specific function, as shown in the figure for the image and diagram of the proximity unit and files. Proximity adjustment is performed on a black and white image. The appearance of any colors in the margins and edges of the image indicates that the adjustment process is incorrect. It does not end and the process of adjusting the correct convergence is complete unless the image appears good in black and white and their gradations. Figure (38-11) is the picture of the deviation and convergence files on a color screen - and the matching panel with its controls appears in Figure (39-11) The device is 26-inch color
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Fineness control:

The process of kinetic and static convergence ensures that the three rays gather on one triple on the color screen. However, it does not guarantee that each ray will reach the center of its phosphorescent color grain, as the ray may strike another neighboring point and induce another color, thus distorting the color information of the image. This is what aims to avoid the process of adjusting the purity (Purity), whose goal is to hit each ray for its own color grain only in all the chromatic triads in all parts of the screen, as in Figure (11-40).

This displacement of the rays is done using a fixed magnetic field with a transverse direction relative to the axis of symmetry of the screen tube. It is not necessary to use an auxiliary device. Rather, the electrodes are placed on the neck of the screen tube close to the convergence electrodes and the main electrodes.

Image distortions:

Since the screen is not circularly curved, we find that the distance that the beam travels in the center of the screen is smaller than the distance that it travels to meet the phosphorescent points on the sides. This is what leads to divergence of rays in the parties more than in the middle. Such distortions appear in the image as a barrel or cushion of pins, as in Figure (11) - (41), and the deflection files that have the shape of (a saddle) work to mitigate these distortions, and the kinetic adjustment process also helps in showing the image as best as possible.