الشروط الخاصة لدارات الخرج الرأسي في التلفزيون الملون الترانزستوري

15-4 Special conditions for vertical output circuits in transistor color television:

Vertical deviation circuits in color TV and monochrome TV are similar, and they differ only in correcting the pincushion phenomenon. In Dynamic Convergence - since the color screen includes three electronic beams in the screen valve, this requires precise tuning to produce a monochromatic image, and there may be a so-called Service Switch to facilitate this tuning.

15-5 circuit to correct the phenomenon of the pin cushion at the top and bottom:

We have mentioned that the pincushion phenomenon is clearly revealed in screens that are relatively large in size, rectangular in shape, and have a large deviation, and it leads to the curvature of the horizontal scan lines at the top and bottom of the screen, as in Figure (6-15), and to correct this distortion in the linear structure (raster) and make the scan lines straight. The maximum correction must be made in both the upper and lower parts of the screen and in the opposite direction - while the scan lines are straight in the center of the screen and do not need correction.

Correction process:

To correct or curve the upper horizontal lines of the screen, a wave of the horizontal saw must be made with a curvature in the upward direction and in the form of a parabola and in the period that suits the time of horizontal scanning of the lines - in order to reach perfectly straight scan lines Figure (7-15) and in the middle of (raster) the lines do not need Horizontal.

To any correction and in the lower half of the screen - we must supply a tooth wave | Vertical saw correction downward for each horizontal line and during the vertical erasure the correction process continues so that it starts in its correct place at the next vertical erasure. Thus each horizontal line is corrected by a parabolic curvature added to the vertical saw wave. The parabolic wave according to the frequency of the horizontal scan is generated and added to the vertical deviation current wave. This is done by the circuit in Figure (15-8) (15-9) (15-10).

Usage of the pincushion correction adapter:

A special transformer (Fig. 11-15) is used to add the parabolic cutting wave of horizontal frequency to a vertical wave of the saw, in which there are three files on a ferrite magnetic circuit, and these files are 1 - horizontal load files 2 - control files or DC bias - vertical load files and their symbol in Chart B-A - The figure shows the amplitude of the horizontal correction wave at the top and bottom of the screen.

The correction is adjusted by changing the page of the coil L. By this adjustment, the page or phase of the arc can be shifted from one side to the other through the screen valve. The coil L and the resistance R3 can correct and adjust the curvature to counteract the curvature of the deformation in the lines, thus eliminating the phenomenon of pincushion, and the permanent magnet in the transformer T may be fixed in place and is to secure the magnetic bias to reduce the necessary winding current (B) and may be changeable in other devices.


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