SU568215A1 - Device for automatically focusing electron beam in pickup tv camera - Google Patents

Description

In the drawing an isofuse structural scheme of the proposed device.

The device contains a television signal sensor 1 connected in series, a video amplifier 2, a high-pass filter 3, a detector 4, a low-pass filter 5, an adder 6, to one of the inputs of which a DC amplifier 7 is connected, and to another the test signal generator 8, and A accumulator 6 through the source of the focusing iOKa (voltage) 9 is connected to the sensor 1; connected to the output of the low-pass filter 5 in series connected barrier filter 1O, tuned to the frequency of the fields (kasheov), narrow-band filter 11, tuned to the frequency of the probe signals, preofazovatel phase code 12, reversible Counter 13 and the converter code-analog 14, the output of which is connected with the input of the DC amplifier 7. The generator also included a double-frequency pulse generator with 15 test signals, the first output of which is connected to another input of the pre-phaser phase code 12, and the second output with the input of the test generator signals 8, {the fugie outputs of which are connected to other inputs of the reversing counter 13.

The device works as follows.

Test actions in the form of a meander from the output of the test signal generator 8 arrive at the adder b, where they are added to the control voltage supplied to its second input from the amplifier 7. Hence the sum of the signals goes to the source of the focusing current (voltage) 9, output the current (voltage) of which varies in accordance with the sum of the voltages acting on the input. Thus, due to the presence of test influences, the focusing current (voltage) changes in one direction or the other from the value specified by the control voltage from the code-analog converter 14, which leads to trial defocusing of the beam.

The video signal from the sensor of the television signal 1 through the video amplifier 2 enters the nm high-pass filter 3, Since the content of the high-frequency components in the video signal spectrum depends on the accuracy of focusing, the components of the video signal, the energy of which largely depends on the focusing accuracy, are output from filter 3 . Due to the presence of test signals on the focusing current (voltage), the high frequency components are modulated by test signals. The signal from the high-pass filter 3 enters through the detector 4 and the low-pass filter 5 to the barrier filter 10, which is tuned to the frequency of the fields (frames). This filter suppresses the very powerful component of the frequency of the fields (frames) contained in the signal. Since the informative component is the frequency of the sampling signal, the signal from the 1O filter goes to the narrowband filter 11 tuned to the frequency of the sampling signals. The phase of the signal at the output of the filter 11 carries information on the extent to which the current value of the focusing current (voltage) is found from the optimum value of the focusing current (voltage). The signal from filter 11 is fed to one input of a phase-to-code converter 12. At its other input are reference pulses from a double-frequency generator of 15 test signals, and short pulses appear at its output, the temporal position of which is determined by the phase of the signal at the filter output 11 with respect to the phase of the test signals. The pulses from the phase-code converter 12 are fed to a reversible counter 13, where, depending on their time position, they are added or subtracted.

Thus, the counter 13 generates a control signal in digital form. The signal from the counter, having passed through the code-analog converter 14, is fed in analog form to the DC amplifier 7, after which it is added to the test signals in the adder 6 and fed to the focusing current source (voltage) 9.

Introduction to the device for automatic focusing of the new functional units of the barrier filter 10, the narrow-band filter 11, the phase-code converter 12, the reversing counter 13, the code-analog converter 14 and. A pulse generator with a doubled frequency of 15 test signals - this device distinguishes itself favorably from the prototype, which makes it possible to increase the focusing accuracy. Decreases are necessary to maintain the device's operability, the amplitude of the test signals, which leads to an increase in focusing accuracy in a dynamic mode. The use of a digital method of generating a control signal eliminates the inertia of the control circuits, which also contributes to an increase in the tuning accuracy of the focusing current (voltage) in the dynamics; com mode.

Claims (1)

Apparatus of the Invention A device for automatically focusing an electron beam of a transmitting television tube, comprising a series-connected sensor of a television signal, a video amplifier, a high-pass filter, a detector and a low-pass filter, an adder, to one of the inputs of which a DC amplifier is connected, and to another a test generator signals, while the output of the adder through the source of the focusing current (voltage) is connected to the sensor of the television signal, which is, in order to increase focusing accuracy, connected to the output of the low-pass filter, are introduced, successively connected, a barrier filter, tuned to the frequency of fields (frames), a narrow-band filter tuned to the frequency of test signals, a phase-code converter, a reverse counter and a converted analogue code, the output of which connected to the input of a DC amplifier, as well as a generator of pulses of twice the frequency of test signals, the first output of which is connected to another input of the phase-code converter, and the second output from the input test signal generator, the other outputs of which are connected to other inputs of the reversible counter. Sources of information, mani in the examination; 1. US Patent No. l cl. 178-.7.2, 1966.