SU385406A1 - DEVICE FOR REPRODUCTION OF COLOR TELEVISION IMAGE - Google Patents

Description

one

This invention relates to photo-index color television image reproduction systems.

A device for reproducing a color television image is known. St. No. 363428.

The purpose of the invention is to reduce distortion when reproducing bright objects with low color saturation.

The proposed device is characterized in that the color information signals are supplied to the inputs of the minimum signal selection cell, the output of which is connected to the control electrode of the color kinescope.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - oscillograms of the modulating signal at point A.

The light from the index tubes of the kinescope / is perceived by the photomultiplier 2. The index signal passes the differential circuit 3, is amplified and limited by the operational amplifier 4.

The feedback unit 5 locks the unit 4 for the time of scanning the color bars by a signal formed from the output signal of the amplifier 4.

The index signal is fed to the switch 6 of one of the incoming color signals and through the delay circuit 7 to the switches S and P of the other two color signals. The signal generated at the output of the switches 6, 8 and 9 is a pulse amplitude modulated signal whose amplitude is proportional to the amplitude of the incoming color signals, and the duration and time shift of the pulses are matched to the structure of the color bars of the screen. Block 10, whose input receives chrominance signals, selects the minimum signal. It can be performed according to the principle of constructing the scheme "OR.

The components of the color signals, equal in magnitude to the smallest of these signals, are passed to the CRT modulator and are folded with a constant offset U. This creates a voltage t / ph., (Fig. 26),

defining background level. This voltage exceeds the set voltage U and depends on the plot of the reproduced image. Switches 6, 8, 9 3 in this case, the signals that represent

the difference between the minimum and any other color signal that exceeds it. Thus, due to the minimum signal extraction unit 10, the modulating signal at point A acquires the form shown

in fig. 26. From waveform matching

The signals shown in FIG. 2a and 26, it can be seen that the introduction of a minimum signal extraction unit into the index system made it possible to increase the background voltage and thereby increase the sipnal / disturbance ratio in the control channel for any sweeps of the modulating signal. The increase in the signal-to-noise ratio is especially noticeable when playing back pnc scenes with a small color saturation (a small difference between the values of the color signals).

Subject invention

A device for reproducing a color television image by author. St. No. 363428, characterized in that, in order to reduce distortion when reproducing bright objects with low color saturation, color information signals are supplied to the inputs of the minimum signal extraction cell, the output of which is connected to the color kinescope control electrode.

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