SU1185649A1 - Device for automatic phasing of frame - Google Patents

Abstract

DEVICE FOR AUTOMATIC PHASE OF FRAME OF A TELEKINO-PROJECTION SYSTEM containing a series-connected key, peak detector, differentiating unit and control pulse shaper, the first key input being input 0 Video Cmpoff b / e cuHitpo-axis / f f wave (dext8ojtjone), I over-set, I / de ject, Idone, I, I, I, I and I, I, I,… In order to improve the accuracy of frame phasing, a gating pulse generator and a controllable delay unit are introduced into the device, the first input of which is connected to the output of the control pulse generator, second The second input is with the second key input and with the output of the gating pulse generator, the third input is connected to the first input of the gating pulse generator, with the second input of the peak detector and is the input of a frame pulse, the fourth input is connected to the second input of the gating pulse generator and is the input of lowercase sync pulses, and the output is the output of the device. (L 00 cd Od 4iib fpae-l

Description

The invention relates to television technology, in particular to systems designed to display movies on television (telekino).

The purpose of the invention is to improve the accuracy of frame phasing in a device for automatically phasing a frame of a teleprojection system.

FIG. Figure 1 shows the structural electrical circuit of the device for automatic phasing of a frame of a telekin projection system; in fig. 2 - timing diagrams for the operation of the device.

The device for automatic phasing of the frame of the TV-film projection system (Fig. 1) contains a key 1, a generator of 2 strobe pulses, a peak detector 3, a differentiating unit 4, a driver 5 of control pulses, a block 6 of controlled delay.

The device for automatic phasing of the frame of the TV-film projection system works as follows.

The negative-polarity video signal (Fig. 2a) from the television signal sensor of the telekinoprocession system is fed to the first (signal) input of key 1, the second (control) input of which receives gating pulses from the output of the gating pulse generator 2, which is triggered by a personnel pulse (Fig. 26) and generates at the output four gating pulses per frame (Fig. 2c), which coincide in time with the inter-perforation intervals on the film (Fig. 2). This is achieved by the fact that the frame pulse, the triggering generator of 2 gating pulses, is formed by the sensor from the perforations of the film (from every fourth hole), and in the generator of 2 gating pulses the frame pulse is delayed by counting from the moment of its arrival the necessary number of horizontal sync pulses received to the second input of the generator 2 gating pulses. Further, the delayed frame pulse is normalized in duration and is repeated three more times at intervals corresponding to the gap between the perforations of the film.

Thus, at the output of the switch-1, video signal samples (Fig. 2d) are formed, which most likely coincide with the interframe gap and arrive at the first (signal) input of the peak detector 3, at the output of which a signal of the form is formed (Fig. 2e) . The peak detector 3 is reset by the second input by a frame pulse (Fig. 26).

In order to ensure maximum noise immunity, the time constants of the peak detector 3 are selected from the following relationships:

TS TS "ТР

... 10Tk, (1)

where Tz, Gr is the constant charge and discharge times of the peak detector 3; Te line length; TD - frame duration. In this case, the duration of the gating pulses (Fig. 2c) is chosen equal to

0 10-20 T ,.

After differentiation of the signal (Fig. 2d) from the output of the peak detector 3, pulses are generated at the output of the differentiating unit 4 (Fig. 2e), which triggers the control pulse shaper 5, which can be implemented as a single vibrator and normalizes the input pulses in duration and amplitude ( Fig. 2g).

Pulses from shaper 5 output

0 control pulses are fed to the first input of the controllable delay unit 6, the second input of which receives gating, the third personnel input, and the fourth input to the lower clock sync pulses. The last (in the interval between frame pulses (Fig. 26) of the control pulses (Fig. 2g) corresponds to the interframe gap, the control delay block 6 performs the counting of pulses (Fig. 2g) in the interval between two frame pulses (Fig. 26), based on what is concluded, the magnitude of the mismatch between the frame pulses and the interframe gap on the film, which can be O, 1/4, 1/2 and 3/4 of the frame duration (Tien value

5 of FIG. 2g). According to the results of Tizi’s assessment, in block 6 a frame sync pulse delayed by the corresponding value is generated (Fig. 2h). The time delay is formed in the control delay block 6 by calculating the normalized number of horizontal sync pulses input to its fourth input. The frame sync pulse generated in this way can be used to force the buffer frame memory addresses to trigger frame scanning, etc.

Thus, high phasing accuracy in the proposed device is achieved due to the fact that as reference

The 0 pulses in it use the pulses from the perforation sensor and the delay of the personnel impulse is carried out for exactly a fixed time interval (1/4, 2/4, 3/4 of the frame duration). Immunity, and hence stability

5 synchronization is ensured by gating only those portions of the video signal that most likely contain a signal from an interframe gap

as well as the choice of the duration of the strobe pulse and the constant charge and discharge times of the peak detector. Since the video signal analysis and phasing are performed within two frames, this ensures high image quality: the synchronization failure becomes almost imperceptible to the viewer.

Claims (1)

A device for automatic phasing of a frame of a television projection system, comprising a series-connected key, a peak detector, a differentiating unit and a driver of control pulses, the first key input being a video signal input, characterized in that, in order to increase the accuracy of phasing the frame, a strobe pulse generator and controlled delay unit, the first input of which is connected to the output of the control pulse shaper, the second input - with the second key input and with the gene output Rathore strobe pulses, a third input coupled to the first input of the strobe pulse generator, a second input of the peak detector and is the input frame pulse, a fourth input coupled to a second input of the gate pulse generator and is input to the horizontal sync pulses, and the output is an output device. momentum Fig.!