SU960997A1 - Method of measuring non-linearity of crt electron beam deflection - Google Patents

Description

(5) METHOD FOR MEASURING NONLINEARITY OF ELECTRON BEAM ELECTRON ELECTRON BEAM

one

The invention relates to a radio measuring technique, namely, to determining the nonlinearity of the electron beam deflection of the electron beam tubes (CRT).

A known method for measuring the nonlinearity of the electron beam deviation in a CRT with electrostatic deviation consists in forming an image of the signal in the center of the screen and comparing its size with the size of the same signal in the checked screen sections using a scale grid. The comparison is made by combining the image of the signal with the scale grid Cl 1

The disadvantage of this method is low measurement accuracy due to geometrical distortions of the signal image at the edges of the screen, visual comparison of the signal size and the scale grid. Using a switch to alternately connect a calibrated TUBE

signal and sweep to deflection plates of a CRT for measurement along the axes X and Y increase their error due to the presence of transients.

There is also known a method for measuring the nonlinearity of the electron beam deviation in a CRT with electrostatic deviation, which consists in shaping the image of a signal in the center of the screen and comparing its size with the size of the image of the same signal in adjustable portions of the screen using a scale grid forming the image of the signal with pulses in the form of a spiral, filling with the working part of the screen. In this case, the magnitude of the nonlinearity is judged by comparing the number of lines between the nodal points of the said grid in the scanned screen areas. The lines are counted by determining the number of pulses forming a spiral between the nodal points of the large-scale network 2.

The disadvantages of this method are the large error and relatively low reliability of the measurement.

The aim of the invention is to improve the accuracy and reliability of measurement.

This goal is achieved by the fact that according to the method of measuring the nonlinearity of the electron beam deflection of the electron-beam tube, which involves deflecting the electron beam, forming on the screen an image of scanning lines and comparing the number of lines on different screen sections using a scale grid, the image of the scanning lines is formed using a digital rectangular the raster filling the working part of the screen is determined by the electrical coordinates of each nodal point of the scale grid relative to the beginning of the frame and the beginning of the corresponding line scan, and the number of lines on different parts of the screen along the vertical and horizontal bars of the scale grid are defined as the difference of the same electrical coordinates between the nodal points.

FIG. 1 shows a CRT screen with a superimposed grid on it, at the nodal points of which there are superimposed miniature optical sensors; in fig. .2 - voltage waveforms that explain the principle of operation of 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 of the screen it is aligned with the center of the scale grid, and the horizontal of the scale grid passing through its center is parallel to the scan line of the temporary deflection plates of a CRT. 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 vertical and horizontal lines of the scale grid is chosen arbitrary, but strictly constant, which ensures the constancy of the distance between the nodal points of the scale grid in both the vertical and horizontal directions. Step between horizontal and

The verticals of the scale grid can be selected and different, but its essential condition is strict constancy.

Next, for example, from the lower left corner in the plane of the CRT screen from point O (Fig. 1), the tube's electron beam is turned up to the right side of the digital rectangular raster on the screen, which is achieved as a result of feeding on a vertically and horizontally deflected CRT plate linearly variable st; foam stresses, respectively, are line U (Fig. 2a),

and personnel} (Fig. 26) scans.

In addition, each subsequent increment of the stepwise voltage of the frame and line scan is chosen so that between the two adjacent nodal points of the scale grid the specified resolution is provided. So, for example, if at the cell size of the scale grid

lOitlO mm stacks 100 or 200 steps, IJ sweeps, or the resolution is 0.1 and 0.05 mm, respectively.

At times t.

t pet

electron beam slit nodal points, for example, respectively in the order of g, b, b5 in microsensors installed at the marked points, there are pulses of the mark U (Fig. 2c), Od (Fig. 2d) and Ug- (Fig. 2e) commands for storing the electrical coordinates of the marked points.

Claims (2)

Each point has two coordinates - one coordinate at the beginning of the corresponding line scan, numerically equal to the number of the step U at the moment of the pulse of a mark along the direction of the Y axis, respectively, for the point rk - Ug4 (Ufi, Fig. 2e); in - Ur. (U-7, fig.2zh); В5 - УЛ (Fig. 2z), the other coordinate in the direction of the X axis is numerically equal to the number of the vertical scanning stage U from the point O, respectively, for the point r -, ф11г. 2i), VC - FIG. 2k), B5 - XpjVU., FIG. 2e). Obtaining the electrical coordinates of the nodal points of the scale grid is also possible when scanning the electron beam into a rectangular raster with two linear sawtooth stresses, then determining the time interval between the points of interest and converting it into a number of pulses. The nonlinearity of the deviation is a dimensionless dimension. According to GOST 19785, the relative non-linearity value H in percent is determined by the expression v-vs; °°° where S is the sensitivity to deviation, measured at a distance equal to 25 from half of the working part of the screen, Sj is the sensitivity to deviation, measured at a distance 75 of half the working part of the screen. The deviation nonlinearity is measured along the axes X and Y, but can be measured at additional points on the CRT screen. Define the nonlinearity of the deviation according to GOST 19785-7 (fig. Assuming that the large-scale horizontal and vertical grid has an equal step t (them), for example, along the X axis along the line.) Differential sensitivity 5 measured at a distance of 25 o half of the working part screen, i.e. G, -G. expresses, for example, on a segment e 4 {: lmAk HH / V-A / Vr4 / CXr3-Xr4) K fZ where I is the distance between the nodal points X is the electrical coordinates of G% G4 . Gd on horizontals Ga and Gd-gd at the counts of the line of the steps of personnel scanning and (Fig. 26); the maximum sweep voltage ratio U, defined as the quotient of the amplitude value of this voltage and the number of sweep steps, is the differential sensitivity, measured at a distance of 75 from half of the working part, of the screen, i.e. for example, in the segment r-g. It is expressed as СХг, -Хг) Н Substituting the expression (2) and (З) in the expression (1 7 and performing mathematical transformations, we get c о) - (Хг,-ХгО; l. И Хгг-Хг4 () 100 Vo But But expression (k) is the number of frame sweep steps (Fig. 26) placed along, -9Rontories between points g and g are numerically equal to the difference in electrical coordinates of these points horizontally, and X (-Xp is respectively the difference of electrical coordinates between points g. the geometrical distances between these points are equal. Based on the analysis of expression (4), it can be concluded that the magnitude is nonlinear The deviations in the CRT at any site in the horizontal direction can be judged by comparing the number of lines between the nodal points of the scale grid in the center of the screen and the nodal points in the checked areas of the screen horizontally, provided that the pitch between the nodal points is strictly constant. also when determining the nonlinearity of the vertical deviation of the m (dwr. 1). The proposed method for measuring the nonlinearity of the deviation of a CRT in comparison with the known one allows to increase the accuracy and reliability of the measurement of the indication of this parameter (and, when measuring the nonlinearity of the deviation, the shape of the screen is insignificant, as well as automating the measurement process, significantly reducing the time costs) Formula of the Invention in different parts of the screen with the help of a scale grid, in order to improve the accuracy and reliability of the measurement, the image of the scanning lines is formed using a digital rectangular raster 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 line scan, and the number of lines in different parts of the screen along the vertical and horizontal scales grids are defined as the difference of the same electrical coordinates between the nodal points. Sources of information taken into account during the examination 1. Mirsky G.Ya. Electronic measurements. M., Energie, 1975, p. with. 132.. . 2. USSR author's certificate No. 661639, cl. H 01 J 9L2, 1979 (prototype) ..