SU1624559A1 - Method for measuring the nonlinearity of electron beam deflectionin cathode-ray tubes - Google Patents

Abstract

The invention relates to a radio measuring technique and can be used in testing deflection systems of cathode ray tubes (CRT). The purpose of the invention is to improve the accuracy of measuring nonlinear distortions of a frame reamer by increasing the number of rows between nodes of a large-scale network. A large-scale grid is superimposed on the CRT screen, the nodes of which are equipped with miniature optical sensors. On a CRT screen, a rectangular raster is reproduced, and the ratio of the horizontal to frame frequency differs from the whole number by 1 / K. When measuring nonlinearity in a frame, this is equivalent to an increase in the horizontal frequency by K times and the same increase in measurement accuracy. Such a choice of the ratio of the horizontal frequency to the frame frequency makes it possible to increase the accuracy of determining the nodal points to values determined by the resolution of the CRT and photosensors. 2 Il. fe

Description

This invention relates to a radio measuring technique.

The purpose of the invention is to improve the accuracy of measurement of nonlinear distortion of the frame.

Figure 1 shows a CRT screen with a superimposed grid on it, at the nodal points of which miniature optical sensors are installed; Fig. 2 shows oscillograms of voltages explaining the proposed method.

The method is carried out as follows.

The scale grid, which is external to the CRT, with mutually perpendicular horizontal and vertical lines (the working field of the CRT is limited to two extreme horizontal lines and vertical scales of the scale grid) is superimposed on the screen in such a way that the center the screen is aligned with the center of the scale grid, and the horizontal of the scale grid passing through its center is parallel to the scanning line of lines. At the points of intersection of the contour lines and verticals of the scale grid, miniature optical sensors with a given resolution, facing the CRT screen, are installed. The step between the horizontals and the verticals of the scale grid is chosen arbitrary, but strictly constant both horizontally and vertically. Then, for example, from the lower left corner in the plane of the CRT screen and point 0 (see FIG. 1), the electron beam of the CRT is directed into the rectangular raster from bottom to top and from left to right, which is achieved by applying sync pulses to the deflecting CRT system Ui (see FIG. 2a) and

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personnel U2 (see Fig.26) frequencies. The ratio of the horizontal frequency to the frame

differs from integer by IT value,

for example, This is equivalent to measuring the non-linearity of a frame by increasing the line frequency by a factor of K, for example, by 10, and to the same increase in measurement accuracy. At instants of time ti, ta, and ta by the electron beam intersection of the nodal points, for example, respectively on the order of Жз, Ж4 and Е4, in the microsensors installed at the corresponding points, impulses of the mark Uz appear (see Fig. 2c), U (see Fig .2d) and Us (see Fig.2d), the temporary position of which is Ati, Atz and At3, i.e. The electrical coordinates of these points are determined relative to the personnel or horizontal pulse by a frequency meter in the period determination mode. The coordinate of any of the nodal points consists of two parts: At is the distance of the corresponding personnel pulse from the first following horizontal and A t is the distance from this horizontal symi pulse to the corresponding mark. Obviously, for sensors lying on the same horizontal line, At / A t. Therefore, the difference in their electrical coordinates does not depend on whether the ratio of the horizontal frequency to the frame integer is. Sensors that are not lying on the same vertical give impulses not only in different lines, but also in different frames. At the same time, for them the constant fractional part of the number At remains, and At and the number of lines (i.e. the whole part A t) are different and depend on nonlinear distortions along the frame. Therefore, the number of lines placed horizontally between two nodal points is proportional to the difference in electrical coordinates of these nodal points relative to the horizontal sync pulse. The number of lines stacked vertically between two nodes, i.e. frame, proportional to the ratio of the difference of the electrical coordinates of these points to the horizontal frequency period

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Consider the case when the nodal points of the first horizontal a (0-8) coincide with the 1st line of the first frame. In the next frame, they no longer coincide with any single scanning line, since the relation between the horizontal and vertical frequencies is chosen by the number of non-integer and, therefore, the beginning of the second frame takes a different position relative to the horizontal sync pulse than the beginning of the first frame. Let the points of the second horizontal line b (0-8) coincide in the fifth frame with the (1 + m) -th line. Then, if the ratio of the horizontal frequency to the frame one differs from

integer, this means that between these horizons there are m integers and four tenth lines. Such a choice of the ratio of the horizontal frequency to the frame frequency allows a significant increase in the accuracy of determining the coordinates of nodal points in a CRT (up to the values determined by the resolution of the CRT and photosensors).

Claims (1)

Invention Formula A method of measuring the nonlinearity of the electron beam of a cathode ray tube, which consists in forming on the screen of a rectangular raster scanning lines, filling the working part of the screen, determining the electrical coordinates of each nodal point of the scale grid relative to the beginning of the frame and beginning of the corresponding horizontal sweeps and comparing the number of lines on different parts of the screen by subtracting the electrical coordinates of the nodal points, characterized in that, in order to improve the measurement accuracy of non-linear zheny on the frame, the ratio of line and frame frequency is set to nonintegral rational number, and electrical nodal points the coordinates determined for pure lo frames not less than the inverse of the fractional part of the ratio of horizontal to vertical frequency.