SU1753620A1 - Method of measuring geometric distortions of tv raster - Google Patents

Abstract

This invention relates to a measure of the geometric distortion of a television raster. The purpose of the invention is to improve the accuracy of measuring geometric distortions of a television raster. The method of measuring geometric distortions of a television raster concludes that a raster is formed on the screen of a cathode ray tube (CRT) by successively deflecting the electron beam in rows and frames across the screen of a CRT, converting the light raster from the CRT screen into an electrical signal (ES), measuring ES parameters characterizing the maximum and minimum values of the electron beam passage time symmetrically arranged horizontally and vertically with respect to the axes of the CRT screen of photosensors, and the difference is measured between the obtained maximum and minimum values of the ES parameters. The goal is achieved by the fact that during the formation of a raster on a CRT screen, each frame is shifted relative to the previous one in the direction of the frame scan by the value -rj & . where N is the number of frames: - the offset of the lines in each frame, and measure the parameters of the received ES for the number of frames not less than N. 1 Il.

Description

The invention relates to television engineering, specifically to the measurement of geometric distortion of a television raster.

The purpose of the invention is to improve the accuracy of measuring geometric distortions of a television raster.

The drawing shows a CRT screen with a rectangular mask superimposed on its working part.

The method of measuring geometric distortions of a television raster is that a raster is formed on the screen of a cathode ray tube (CRT) by successively deflecting an electron beam in rows and frames across the screen of a CRT, converting a light raster from a CRT screen

The electric signal parameters, which characterize the maximum and minimum values of the transit time by an electron beam symmetrically horizontally and vertically relative to the CRT screen axes of photosensors, are measured and the difference between the maximum and minimum values of the electrical signal parameters measured on the screen CRT shift each frame relative to the previous one in the direction of the frame scan by

 where N is the number of frames, D | - offset lines in each frame, and measure About

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parameters of the received electrical signal for the number of frames not less than N.

The drawing shows the working part of the screen CRT.

A device that implements a method for measuring geometric distortions of a television raster contains a screen 1 of a cathode ray tube (CRT), a stencil 2, photosensors 1.1 - 1.8 ... 6.1 - 6.8.

The device works as follows. ...; :.

On screen 1, a CRT forms a rectangular raster by sweeping the electron beam from the lower left corner of the screen plane from bottom to top and from left to right, by applying horizontal and frame sync pulses to the TV sync inputs. In this case, the frequency of horizontal pulses exceeds the frequency of personnel pulses by a non-integer rational number of times. Therefore, the line with the same number in each subsequent frame will be shifted relative to its previous position and will occupy the same position in terms of the number of frames equal to the inverse of the fractional part of the horizontal frequency / frame ratio. This is equivalent to forming a raster from a much larger number of lines on a television screen than is used in this television standard. If the value of the fractional part of the ratio

frequency to frame is

ten

then

the number of lines on the screen increases 10 times, which also increases the accuracy of determining the electrical coordinates of photo sensors located on the horizontal x (i.e. 1.8, 1.8), and hence the accuracy of determining the geometric distortions of the raster ...

The measurement of the transit time of an electron beam between symmetric points is made by switching on the measurement

time indicator with the left (or lower) photo sensor and turn it off at the moment of passing the right (or upper) photo sensor. In this case, the passage time

Claims (1)

5 sections 1.1-1.8 are measured in the same line, and the time of passage of sections a to e can be measured in different frames, which increases the accuracy of their measurements. The proposed method allows to automate the process of measuring geometric distortions on a TV screen with high accuracy of control, which greatly expands the scope of its application. . Invention Formula 15 A method of measuring geometric distortions of a television raster, which consists in forming a raster on the screen of a cathode ray tube (CRT) by successively rejecting the electronic 20 beams in rows and frames on the CRT screen, convert the light raster from the CRT screen into an electrical signal and measure the electrical signal parameters characterizing the maximum and minimum 25 values of the electron beam passing symmetrically horizontally and vertically relative to the axes of the screen of a CRT photo sensor, measure the difference between the maximum values obtained 30 and the minimum values of the electrical signal parameters, characterized in that, in order to improve the accuracy of measuring the geometric distortions of a television raster, when forming a raster on 35, the CRT screen shifts each frame relative to the previous one in the direction of the frame sweep by a value of - 1, where N is the number of Frames, A1STp is the offset of lines 40 in each frame, and the parameters of the received electrical signal are measured for frames not less than N. and G.8 ABOUT