SU1160606A1 - Line scanning system - Google Patents

Abstract

A STREET SCAN device, containing a series-connected preselector, an amplitude selector, a frequency and phase auto-tuning unit, a master oscillator and an output unit, the first output of which is the device output, and the second output connected to the second input of the frequency and auto-tuning unit, the second output of the amplitude selector through the key is connected to the common length, and the pre-selector input is the device input, characterized in that, in order to increase the reliability of the horizontal scanning device by blocking the amplitude selector in the absence of the video signal at the input, it introduced integrator limiter-amplifier, a rectifier and a comparator connected in series between the output terminal and the second pre-selector key input, the second input of the comparator i is input to the reference voltage. (L

Description

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The invention relates to television technology and can be used in scanners of television receivers.

A line-scanning device is known, comprising a series-connected amplitude selector, a phase detector, a low-pass filter, a master oscillator, and an output unit, the output of which is connected to the second input of the phase detector 1.

However, the device lacks noise immunity with respect to impulse noise and interference with the network frequency.

Closest to the present invention is a horizontal scanning device comprising a series-connected preselector, an amplitude selector, a frequency and phase self-adjusting unit, a master oscillator and an output unit, the first output of which is the output of the device, the second output is connected to the second input of the frequency and auto-tuning control unit , the second output of the amplitude sector is connected via a switch with a common length, and the input of the pre-selector is the input of device 2,

The known device lacks reliability due to the fact that in the absence of a video signal at the device input, chaotic changes in the frequency of the master oscillator under the action of noise are possible, which can lead to failure of the elements of the output block.

The purpose of the invention is to increase the reliability of the horizontal scanning device by locking the amplitude selector in the absence of a video signal at the device input.

This goal is achieved in that a horizontal scanning device comprising a series-connected preselector, an amplitude selector, a frequency and phase self-adjusting unit, a master oscillator and an output unit whose first output is the output of the device and the second output is connected to the second input of the frequency auto-adjusting unit and phase, the second output of the amplitude selector is connected to the common length through a switch, and the input of the preselector is the input of the device, an integrator, an amplifier-limiter is entered, A driver and a comparator connected in series between the output of the pre-selector and the second key input, the second input of the comparator being the input of the reference voltage.

The drawing shows a structural electrical circuit of the horizontal scanning device.

The horizontal line scanner includes a pre-selector 1, an amplitude selector 2, a key 3, a frequency and phase auto-tuning unit 4 (AFC and F), a master oscillator 5, an output unit 6, an integrator 7, a limiting amplifier 8, a rectifier 9 and a comparator 10 .

The line scanner operates as follows.

The television video signal through the pre-selector 1 is fed simultaneously to the amplitude selector 2 and the integrator 7, which selects frame sync pulses, which are then converted by the limiter 8 and rectified by the rectifier 9. The constant reference voltage is fed to the second input of the comparator 10, The second input is supplied with a constant voltage from the output of the rectifier 9.

When a video signal is present at the input of a video signal device, the voltage at the first input of the comparator 10 exceeds the value of the reference voltage at its second input, as a result of which the output voltage of the comparator is low, the key 3 is open and the horizontal sync pulses from the output of the amplitude selector 2 passes to the first input of the 4th frequency control unit and F, resulting in the synchronization of the master oscillator 5, controlling the operation of the output unit 6. The second input of the 4th frequency control unit and the F post 1 lower pulse back go from the second output of the output unit 6.

It should be noted that the synchronization circuit, including in this case block 4 of the AFC and F and the master oscillator 5, can also have a two-loop structure, in which the frequency and phase of the horizontal sync pulses and pulses of the master oscillator are compared first, and then the pulse phase of the master oscillator is compared with phase pulse reverse horizontal sweep.

In the absence of a video signal and the appearance of noise and interference at the device input, the voltage at the first input of the comparator 10 is lower than the reference voltage supplied to its second input, resulting in a high voltage level at the output of the comparator, which opens the key 3, which blocks amplitude selector 2. At the same time, the noise and noise are not fed to the first input of the 4th frequency control unit and F, which ensures normal operation of the master oscillator 5 at a natural frequency close to the nominal frequency yerki

Thus, the proposed device for horizontal scanning of a television receiver allows to increase the reliability of the device in the absence of television.

signal with sync pulses on the limiter input, rectifier and compass by blocking the amplitude operation, providing reliable protection

signal by the selector of the output horizontal block and the newly introduced blocks: the sequence as a whole from the effects of noise

but connected by an integrator, amplification and interference.

1160606

Claims (1)

LINEAR DEVICE, comprising a pre-selector, an amplitude selector, a frequency and phase locked loop, a master oscillator and an output block, the first output of which is the output of the device and the second output connected to the second input of the frequency and phase locked loop, the second amplitude output the selector through a key is connected to a common bus, and the input of the preliminary selector is the input of the device, characterized in that, in order to increase the reliability of the horizontal scanning device m blocking the amplitude selector in the absence of a video signal at the input of the device, an integrator, an amplifier-limiter, a rectifier and a comparator are inserted into it, connected in series between the output of the preliminary selector and the second input of the key, while the second input of the comparator is the input of the reference voltage. Uo / 7 h