SU555378A1 - Extreme electron beam focusing control system - Google Patents

Description

one

The invention relates to systems for automatically adjusting the focusing voltage (current) of transmitting television tubes and can be used in the field of thermal tempering, radar, computer technology for automatic focusing of a read beam in various types of electron-beam devices.

Extreme control systems containing the quality control object, the trial (sinusoidal influence of the rectangular) signal and the reversing actuator, most often a trigger Ij,

Pulse control systems containing a comparison unit, a signal error shaping unit, a test signal generator, the And element, and a convertible counter actuator 2 are known.

There are known automatic fsjusirovka, operating on the principle of maximizing the high-frequency components in the spectrum of the video signal, containing a filter

high-pass, low-pass filter, power amplifier, test defocus unit, switch, minimum limiter, maximum limiter, optical and electrical focus actuators, 3j.

A disadvantage of the known system is the low focusing accuracy of the electron beam.

A focusing system is also known comprising a television signal sensor, a first amplifier, a detecting and filtering unit, a fixation unit for gating, a second amplifier, a focusing current source, whose outputs are connected to the corresponding inputs of a television signal sensor, a test pulse generator, the first output of which is through a block the formation of gating pulses is connected to the corresponding inputs of the fixation and gating unit, and the reverse trigger, the first output of which through The first counter and the third amplifier are connected to the control input of the television signal sensor 4.

In autofocus devices with test signals, the frequency of test signals is chosen from the conditions for minimizing the distortion introduced into the image. For both progressive and interlaced scanning, the frequency of the test signals is two times lower than the frequency of the half-frames. In this case, the test signals cause the frequency component in the video signal spectrum to be the frequency of the test signals and which contains information about the focus quality.

This automatic focusing system works with a significant amplitude of test signals, which increases the search loss, reducing the focusing accuracy. A change in the focusing current when the test pulses cause not only deterioration of focusing, but also a noticeable shift and rotation of the raster, which further degrades the visual clarity of the image and leads to rapid fatigue of the operator observing a shaky pattern. The amplitude of the test signals decreases to increase accuracy and reducing the interfering effect leads to a narrowing of the dynamic range in which the operation of such systems is possible.

The aim of the invention is to improve the accuracy of the system of extreme control of electron beam focusing.

This is achieved by installing the first and second elements AND in series with the waiting multivibrator, the second counter, the decoder and the time master oscillator, the output of which through the first element AND is connected to the input of the focusing current source and through the second element And - with the corresponding inputs of the first counter and the reverse trigger, the second output of which is connected to the corresponding inputs of the waiting multivibrator and the second counter, the second and third you ode test signal generator are connected respectively to the second inputs of the first AND element and latch reversal, the output of the second amplifier is connected to the second input of the AND gate, the second output of the master oscillator the time connected to a control input of the second counter.

The drawing shows a block diagram of the system, where a 1-sensor of a television signal, 2-4 first, second and third amplifiers, 5 is a detection and filtering unit, b is a fixing and gating unit; 7 — gating pulse shaping unit; 8 — test signal generator; 9- focusing current source, 10 and

11 - the first and second elements And; 12 and 13 - the first and second counters; 14-reverse trigger; 15 - waiting multivibrator; 16 - deshi1 | rator; 17 - time master oscillator.

The proposed system works as follows.

A square-shaped test signal from the output of the test signal generator 8

through the first element AND 10, controlled by the second input by the output signal, the time of the master oscillator 17 is fed to the input of the focusing current source 9, the output current of which varies in accordance with their effect on that and the other side from the set value, which results in supplying , such a current on the sensor of the television signal 1 to the test defocusing of the electron beam. Video

From the output of the sensor of the television signal 1 is fed to the input of the first amplifier 2, which amplifies in the frequency band the corresponding high-frequency part of the video signal spectrum. The energy of high-frequency components in the video signal spectrum largely depends on the accuracy of focusing. Due to the presence of test signals on the focusing current, the high-frequency components are modulated

with the frequency of the test signal. From the output of amplifier 2, the signal modulated by the frequency of the test signal is fed to the input of the detecting and filtering unit 5, at the output of which a signal is obtained

the frequency of the test signal, the phase of which carries information about which side of the optimum value of the focusing current (voltage) is the current value of the focusing current (voltage).

The received signal is fed to the input of the fixation and gating unit b, to the other two inputs, which receive gating pulses generated by the gating pulse generation unit 7 from the test signal supplied to its input from the test signal generator 8. Short output pulses appear at the output of block 6 whose temporal position is determined by the phase of the signal at the output of block 5 with respect to the phase of the gating pulses, which are rigidly connected in phase with the test signal. Further, the travel pulses are amplified by the second amplifier 3 and through the second element I 11 (if there is

the input of the resolution level supplied from the output is the time of the master oscillator 17) is fed to the input of the first counter 12 containing the code-analogue converter, as well as to the trigger of the reverse 14. On the second

the reverse trigger input 14 provides a test signal from the output of the test signal generator 8. Depending on the phase relationships in which these signals are located, the first output of the reverse trigger 14 produces a signal that, when fed to the control input of the first counter 12, is supplied to another its input to the travel pulses is either the addition mode or the subtraction mode. Next, the counter 12 generates a control signal in a digital form, and its code-analog converter transmits this control signal in analog form. This signal is then fed to the input of the third amplifier 4, amplified and fed to the control input of the sensor of the television signal 1. Thus, the focusing voltage (current) is adjusted to the optimum value. The use of digital signal processing significantly increases the gain of the analog part, without fear of self-excitation, which reduces the static error of the proposed system. In addition to the static error, the accuracy of the automatic focusing system of the cal device 25 of the extreme adjustment device depends on the error caused by the search loss. This error is minimized by determining the moment of extrection of the extreme value of the focusing voltage (current), storing it and then stopping the system - automatically controlling the focusing for some time determined by the time with the generator 17. Because this time is approximately two times For more time required for the system to search for extremum, sufficient secrecy is achieved. its operation is eliminated by the acting-factor of fatigue of the operator, who had previously observed a continuous flickering image. To determine the moment when the extremum is reached, it is proposed to use the fact that the extremum system; after reaching the extreme value of the controlled parameter, the control starts to oscillate around its value with an amplitude of 1-3 steps. In the proposed system, this is expressed by the appearance at the output of a reverse trigger 14 reverse pulses with a periodicity (2-4 Tpr, where Tpr is the period of the test signal, ifo emitted reverse pulses are fed to the input of the second counter 13 where they are counted. At that moment when the code on the counter 13 takes a certain value, at the output of the decoder 16 connected to (the OUTPUT of the reverse counter 13

a pulse appears to start; the time of the master oscillator 17; the time master oscillator 17 produces a stop pulse, the duration of which lies within

minutes The received pulse is applied to the reset of the counter 13, and in addition, the first element And 10 and the second element And 11, which prohibit the passage of the test signal to the source of the focusing current 9, and the pulse pulses on the reverse trigger 14 and the counter 12. memorizing the achieved value of the controlled parameter for the duration of the stop pulse. In order

to eliminate the occurrence of a false stop pulse as a result of the accumulation of random reverse pulses that may occur when the system is working through very large detunings of the controlled

Claims (1)

parameter, they are counted for some time specified by the waiting multivibrator 15. If during this time the code on the counter 13 does not reach the specified value, then at the end of 30 pulses of the waiting multivibrator 15, the back edge of the counter resets 13. Introduction to the automatic control system focusing the electron beam of the new functional units of the future multivibrator, the second counter, the decoder, the time of the master oscillator, the first and second elements And favorably distinguishes the proposed system in automatic focusing control to see. Since, together with an increase in focusing accuracy (1.5-2) times, sufficient secrecy of the system operation is also achieved, and the factor of fatigue of the operator performing the analysis of the observed television image is eliminated. Such a gain in focusing accuracy is particularly important for modern television systems with increased resolution. The invention The system of extreme control of electron beam focusing, containing a television signal sensor, a first amplifier, a detecting and filtering unit, a fixation and gating unit and a second amplifier, a focusing current source, the outputs of which are connected to the corresponding inputs of the television signal sensor, test signal generator the first output of which, through the strobe formation unit