SU882023A1 - Method of measuring non-uniformity of signal through image field of television camera tubes - Google Patents

Description

The invention relates to television and can be used to measure the irregularity of black and white and color television television transmitting signals.

The known method of measuring signal irregularity over the image field of television transmitting tubes, based on projecting the test transmission tube to the target in the form of bright image portions against a dark background, transforming the resulting potential relief using a readout raster into a video signal, measuring the signal of given regions of the television transmitting tube, corresponding to the light areas of the image, when making adjustments to the size and raster alignments for each zmer the part to and subsequent calculation value unevenness 1.

However, the known measurement method takes a long time because of its laboriousness.

The purpose of the invention is to increase speed while eliminating the influence of

non-linear distortions of the reading raster for measurement accuracy.

To do this, according to the method of measuring the signal irregularity over the field of the image of the television transmitting tubes, based on projecting the test table in the form of light areas of the image against a dark background on the target of the television transmitting tube, transform the obtained potential relief using

10 raster to the video signal, measuring the signal of the specified target areas of the television transmitting tube corresponding to the light areas of the image, and then calculating the amount of irregularity before measuring

15 integrates the video signal obtained from predetermined portions of the target of the television transmission tube corresponding to the light portions of the image.

Claims (2)

FIG. 1 shows a structural electrical circuit of the device for implementing the proposed method; in fig. 2 - the image of the test table on the screen of the video monitoring unit. The device contains a test table 1, a lens 2, a transmitting television tube 3, a video path 4, a video monitoring unit (WKB) 5, an integrating unit 6, an indicator 7, a generator of 8 strobe pulses. The essence of the proposed method is as follows. A value proportional to the integral of the signal over the area of each of the bright areas of the image is measured, and the calculations are made by substituting the values of this value into the formula for calculating the irregularity. If we denote the measured value by Q, then by definition GL KJgicdt, where K -. coefficient of proportionality; I. it is the signal current, where, ut charge, read from the switched element; At is the switching time; S is the region of integration determined by the area of the bright part of the image. Of these expressions, we have: a KXi, dt Kf where Q is the total charge read from the area of the bright part of the image. From the above expression it can be seen that the measurable quantity Q does not depend on the rate of scanning of the target by the electron beam and is completely determined by the total charge Q read from the area of the light image area. Substituting the expression for calculating the non-uniformity H value Q, we determine the non-uniformity of the image field: H - O, max. - O-min. The unevenness of H determined from this expression does not depend on nonlinear distortions of the raster, since the value of Q does not depend on the speed of scanning the target. A test table containing bright rectangles on a dark background is projected with the help of lens 2 on the photo layer of the transmitting television tube 3. The signal of the transmitting television tube 3 is fed through videotrack 4 to the VKB 5 and to the integrating unit 6 connected to the indicator 7. Using the generator 8 The strobe pulses connected to the integrating unit 6 and the VCB 5 combine the indicator indicator on the screen of the VCB 5 with the mark of the gating rectangle 9 with one of the bright rectangles of the image 10 as shown in FIG. 2. Read off the indicator indicator 7 - Q ,, nponopi onal signal integral over the area of the gated rectangle. Place the gated rectangle on the adjacent light portion and read the value of Qj. Perform this operation on all bright areas of the image sequentially. Get the sequence of values QI, Oz, ..., Qg. From this sequence, the maximum and minimum value of Q is determined and substituted into the expression for N. The integrating unit 6, necessary for measuring the value of Q, can be performed according to the classical scheme on an operational amplifier. The essential difference of the proposed method of measuring the non-uniformity from the existing ones is that they measure not the instantaneous value of the signal, depending on the scanning speed, but the value of the integral of the Sigal over the area of the bright part of the image, which does not depend on the scanning speed. This eliminates the influence of non-linear distortions of the raster and does not require the adjustment of the size and centering of the raster, as required by a known method. Tests of the proposed method of measuring signal irregularities showed that the time spent on measurements is reduced no less than 5 times as compared with the known method. DETAILED DESCRIPTION OF THE INVENTION A method for measuring a signal irregularity over a field of an image of a television transmission tube, based on projection onto a mouse. the television transmission tube of the test table in the form of bright image areas on a dark background, converting the obtained potential relief using a reading raster into a video signal, measuring the signal of predetermined target areas of the television transmission tube, and then calculating the irregularity value, characterized by , in order to increase the speed while eliminating the influence of non-linear distortions of the reading raster on the measurement accuracy , before the measurement, integrate the video signal, which is given from the given areas of the target of the television transmitting tube, which correspond to the light areas of the image. Sources of information taken into account in the examination, 1. Electronic equipment, ser. 4, ex. 9, p. 139 (prototype).