SU1670804A1 - Device for reproducing tv image - Google Patents

Abstract

A television image reproducing device comprising a series-connected receiving / amplifying unit, a vertical generator and a signal to light converter, the second input of which is connected to the output of the horizontal scanning generator, the input of which is connected to the second output of the receiving and amplifier unit, the third output of which is connected to the input of the detector image contours, with the third input of the signal converter - the light is connected to the output of the output amplifier, characterized in that, in order to increase the sharpness, of the left-view image and reduction of the degree of sharpening of the television image from its contrast, a corrector of brightness distortions and a serially connected threshold block, a corrector of geometric distortions and a shaper of the control signal, the output of which is connected to the input of the output amplifier, and the second input is connected to the output of the threshold the unit whose input is connected to the output of the image contour detector, the input of which is connected to the first input of the luminous distortion corrector, Its input is connected to the output of the geometric distortion corrector, the third input is connected to the output of the threshold unit, and the output of the brightness distortion corrector is connected to the fourth input of the signal-to-light converter.

Description

The invention relates to television, is intended to control indicator cathode ray tubes (CRT) in a progressive or interlaced television (TV) image mode and, in particular, can be used in TV playback devices on a two-gradation CRT screen x) and halftone CRT (in video monitoring devices and TV receivers).

Closest to the invention is a TV image reproducing apparatus comprising sequentially

connected receiver-amplifying unit, vertical scanning generator and signal-to-light converter, the second input of which is connected to the output of the horizontal scanning generator, whose input is connected to the second input of the receiving-amplifier unit, the third output of which is connected to the input of the image contour detector, the third input The signal-to-light converter is connected to the output of the output amplifier, to the input of which, through the automatic gain control unit, the output of the image contour detector is connected

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However, the known device has a low degree of sharpening of the reproduced image and the dependence of the amount of sharpening of the image on its contrast.

The purpose of the invention is to increase the sharpness of a TV image and reduce the dependence of the degree of sharpening of a TV image on its contrast.

For this, a television image reproducing apparatus comprising a series-connected receiving and amplifying unit, a vertical scanning generator and a signal-to-light converter, the second input of which is connected to the output of the horizontal scanning generator, the input of which is connected to the second output of the receiving-amplifier unit, the third output of which is connected An input of the detector of the image contours, the third input of the signal-to-light converter is connected to the output of the output amplifier, and a distortion corrector is introduced. and a serially connected threshold unit, a geometric distortion corrector, and a control signal generator, the output of which is connected to the input of the output amplifier, and the second input is connected to the output of the threshold unit, the input of which is connected to the output of the image contour detector, the input of which is connected to the first input of the corrector of distortion whose second input is connected to the output of the geometric distortion corrector, the third input is connected to the output of the threshold unit, and the output of the brightness distortion corrector is connected with the fourth input of the signal-to-light converter.

FIG. Figure 1 shows the structural electrical circuitry of a TV picture playback device; in fig. 2 is a structural electrical circuit of a threshold unit; in fig. 3 is a structural electrical wiring diagram of the correc- tion of the luminous distortions; in fig. 4 - voltage and current diagrams.

The TV image playback device (Fig. 1) contains a receiving-amplifying unit 1, a horizontal scanning generator 2, a vertical scanning generator 3, an image contour detector 4, a threshold unit 5, a corrector 6 luminous distortions, a signal-to-light converter 7, a corrector 8 geometrical distortions, control signal former 9 and output amplifier 10.

The threshold unit 5 (Fig. 2) contains a full-wave rectifier 11 and a comparator 12.

The corrector 6 brightness distortion (Fig. 3) contains the first delay line 13, the second delay line 14, the first key 15, the second key 16, the inverter 17 and the adder 18.

The TV image reproducing apparatus operates as follows.

The input information of the receiving and amplifying unit 1 receives the original information at the carrier frequency or as a TV signal and is formed into frame and line sync pulses of the required size and polarity, as well as into the TV signal (Fig. 4a). The corresponding sync pulses are fed to the generator 2 line scan and

5, a frame scan generator 3, by means of which a standard image decomposition is provided during its reproduction. In the 4 image contour detector, a TV signal is differentiated (Fig. 46).

The threshold unit 5 (Fig. 2) reduces the dependence of the sweep applied to the second input of the imaging unit 9 pulses on the image contrast. Otherwise, as is the case in the known device, a full stop of the scanning beam is not ensured during the reproduction of the image contours, as a result of which the unsharpness reduction in the horizontal scanning direction is small. The input signal (Fig. 46) is rectified in a full-wave rectifier 11 and converted into rectangular pulses of constant amplitude (Fig. 4c) in the comparator.

5 12.

These pulses in the driver control driver 9 are converted to a sawtooth voltage (Fig. 4e). The latter is converted by the output amplifier 10 into a deflecting current of the same form, flowing through additional horizontal deflection coils, which are part of the deflection system of the signal-to-light converter 7. The rate of current change in the additional horizontal deflection coils during the reproduction of the image contours is chosen such that the rate of deflection of the beam under the influence of the additional coils

0, the horizontal deflection is equal in magnitude, but opposite in sign to the speed of the deflection of the beam under the influence of the deflecting current (Fig. 4e) flowing through the horizontal coils,

5 which are part of the signal-to-light transducer deflection system 7. Due to this, the scanning beam in the signal-to-light converter 7 during the reproduction of the image contours stops, and the corresponding zone

Unsharpness takes the minimum in the direction of the line scan size. To prevent spatial displacement of the image contours on the screen of the 7 signal-to-light converter, the geometric distortion corrector 8 determines the interpulse average component (Fig. 4g) of the signal from the output of the threshold unit 5.

Under its influence, a reverse stroke of sawtooth pulses with controlled steepness generated in the driver 9 of the control signal is formed (Fig. 4e). As a result, the average line scan speed, due to the combined effect of both deflecting currents (Fig. 4d) between any pair of pulses (Fig. 4c) corresponding to the contours of the reproduced image, remains unchanged. In order to prevent luminous distortions caused by the inconsistency of line-scan speed, in the corrector 6 luminance distortions (Fig. 3) the scale of the video signal under the influence of input correction signals (Fig. 4c, g) decreases when playing contours, and the background brightness between the pulses is adjusted according to on the value of the interpulse average component (Fig. 4h).

The brightness of any portion of the image reproduced by the signal-to-light converter 7 is directly proportional to the magnitude of the TV signal and inversely proportional to the scanning speed. Therefore, in order to eliminate luminous distortions due to the inconsistency of the line scan speed, the TV signal must be multiplied by

proportional sweep speed. Since the control changes in the line scan speed (Fig. 4c) are quantized into two levels and, accordingly, the values of the line scan speed during background and contour reproduction differ significantly in size, the TV signal during the reproduction of the image contour is multiplied by one a fixed value, and during background reproduction, another fixed value. For this, two alternate keys 15 and 16 are used, alternator 18, in which the input signals summarize 5 s in the required proportion. The alternate operation of the keys 15 and 16 is ensured by the opposite polarity of the rectangular pulses supplied to their control inputs from the output of the threshold unit 5 and the inverter 17.

0 Lines 13 and 14 of the delay in the corrector 6 Luminance distortions compensate for the time delay of the signal in the corrector 3 geometric distortions (for the horizontal scanning period) that occurs when

5 forming signals of the inter-stimulus average component.

The invention provides for a full stop of the scanning beam at the time of reproduction of the image contours than

0 significantly reduces the effect on the magnitude of the resulting blurring zone, the insufficiently high resolution of the transmitting TV equipment and the limited band of the communication channel. As a result, the sharpness of reproducible TV images increases approximately B two times.

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Claims (1)

A TELEVISION IMAGE PLAYBACK DEVICE containing a series-connected receiving / amplifying unit, a vertical scanning generator and a signal converter with a light, the second input of which is connected to the output of a horizontal scanning generator, the input of which is connected to the second output of the receiving-amplifier unit, the third output of which is connected to the input of the contour detector , while the third input of the signal-to-light converter connects