JPS6134314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is useful when reproducing a recording track of an FM modulated video signal over two tracks, or when reproducing a partially off track, such as in slow motion mode or still in a helical scan type VTR. The present invention relates to a video signal reproducing device that makes noise band parts generated in video signals reproduced in motion mode as easy as possible to see.

Previously, the noise band part in slow motion mode and steel motion mode was very unsightly as it became a black or white impulse nozzle, and measures were taken to remove this part, but it was still unnatural and unsightly. There was a drawback.

The present invention eliminates these drawbacks and
DESCRIPTION OF THE PREFERRED EMBODIMENTS The video signal reproducing apparatus of the present invention will be described below with reference to drawings of embodiments.

FIG. 1 is a basic configuration diagram showing the principle of the present invention.

In the same figure, the video signal applied to input terminal 1 is FM modulator 2 with an FM frequency deviation of 3.4MHz.
It is 4.4MHz. converted to FM signal. This FM
The signal is amplified to the level recorded by the recording amplifier 3, and is transmitted to the rotary transformers 6 and 7 by turning the movable pieces of the recording/reproducing switches 4 and 5 to the R side. The rotary transformers 6 and 7 connect the signal paths on the stationary side and the rotating side by magnetic flux, and in this case, transmit the FM signal to the rotating side. This FM signal is transmitted to the magnetic head 10 via the rotating shaft 8 and the head bar 9.
and 11, and recorded on the magnetic tape 13. Note that the magnetic tape 13 is attached to a tape guide 14.
and 15, and travels in the direction of arrow 16. It is assumed that magnetic heads 10 and 11 rotate in the direction of arrow 12. A recording pattern recorded on the magnetic tape 13 is shown in FIG. In the figure, recording tracks 50, 51, 5
2 and 53 indicate that FM signals are recorded here.

During reproduction, the reproduction signals obtained by scanning the recording tracks 51 and 52 by the magnetic heads 10 and 11 are supplied to the recording/reproduction changeover switches 4 and 5 via the head bar 9, the rotary shaft 8, and the rotary transformers 6 and 7. . Since the movable pieces of the recording/reproduction changeover switches 4 and 5 are both turned to the P side, the reproduced signal is supplied to the field changeover switch 17. Since the field changeover switch 17 is changed over for each field, a continuous reproduction signal is obtained at its output terminal. This reproduced signal is demodulated into the original video signal by the FM demodulator 19, amplified to a required level by the output amplifier 20, and supplied to the output terminal 21. The above is a case where the magnetic tape 13 is running at a predetermined speed in the direction of the arrow 16.

Next, the still motion mode, that is, the case where the magnetic heads 10 and 11 rotate in the direction of arrow 12 even though the magnetic tape 13 has stopped running will be described. In this case, magnetic heads 10 and 11 scan a track 54 shown in broken lines in FIG. The output terminal of the regenerative amplifier 18 is
The waveform of the PM signal shown in is obtained. . When such an FM signal is demodulated by the FM demodulator 19, a video signal including a noise band N is obtained as shown in FIG. 3B. At this time, a pulse signal P is obtained in the noise band portion at the output end of the noise band portion detector 22 connected to the output end of the regenerative amplifier 18, as shown in FIG. 3C. The noise band portion detector 22 is configured to detect the envelope of the FM signal obtained from the output of the regenerative amplifier 18, and output a pulse signal P when the envelope falls below a certain set value. This pulse signal P
By being supplied to the resistor 24 of the limiter circuit 23 connected to the output terminal of the FM demodulator 19, the transistor 26 is turned on, and the diode limiter 2
7 and 28 work. In other words, the noise band N of the output signal of the FM demodulator 19 as shown in FIG.
Since the upper and lower tips of the are grounded via the capacitor 29, diode limiters 27 and 28, and transistor 26, the noise band portion N' is limited to be smaller than the amplitude of the video signal as shown in FIG. 3D. A signal is available at the input of the output amplifier 20. Such a video signal is amplified by an output amplifier 20 and supplied to an output terminal 21. Although the still motion mode has been described above, the same applies to the slow motion mode and the case of partial mistracking.

As described above in detail, the video signal reproducing device of the present invention has the feature that unsightly noise bands are reduced by limiting the amplitude of the impulsive noise band portion in, for example, still motion mode or slow motion mode. Furthermore, since the noise band portion is not completely removed, the information contained therein is at least transmitted and the naturalness of the video signal is maintained.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing the principle of the video signal reproducing device of the present invention, FIG. 2 is a diagram showing an example of a recording pattern on the magnetic tape 13, and FIGS. 3A, B, C, and D.
2 is a diagram showing the waveform of a reproduced signal and its change. FIG. 19...FM demodulator, 22...Noise band partial detector, 23...Limiter circuit, 24...Resistor, 26...Transistor, 27...Diode, 28...Diode.

Claims (1)

[Claims] 1. Noise band parts are added to the reproduced video signal by scanning and reproducing a track on which an FM modulated video signal is recorded, or by scanning and reproducing a plurality of tracks. In a video signal reproducing device that generates a noise band that occurs in the reproduced video signal, a circuit that detects a noise band portion that occurs in the reproduced video signal, and only the noise band portion is operated by the output from the noise band portion detection circuit, and the noise band that occurs in the reproduced video signal is operated. A video signal reproducing device comprising a limiter circuit which makes the amplitude of a portion smaller than the amplitude of the reproduced video signal by AC coupling. 2. The limiter circuit includes a limiter element including an AC coupling element arranged in parallel to the transmission path of the reproduced video signal, and a switch element arranged in series with the limiter element that operates only during the period when a noise band is generated. A video signal reproducing device according to claim 1, characterized in that: