JP2508402B2 - Magnetic playback device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus (hereinafter referred to as “VTR”), and more specifically, a reproduced image with a large amount of vertical bending or shaking, that is, a reproduced video signal. The present invention relates to a magnetic reproducing device for improving the image quality of an image having a large amount of fluctuation in horizontal frequency.

[Conventional technology]

FIG. 2 is a feed-forward type FM time base collector (FM-) using a conventional flywheel oscillator (hereinafter referred to as “FWO”) in a conventional magnetic reproducing apparatus.
FIG. 3 is a block circuit diagram of a TBC) circuit. In the figure,
(1) is an input terminal for a reproduced FM video signal, (2) is an FM demodulator, (3) and (4) are horizontal sync signal extraction circuits for extracting a horizontal sync signal from the FM demodulated video signal, and (5) is An AFC circuit that removes high-frequency fluctuations from the frequency fluctuations of the horizontal sync signal, (6) a phase comparator that compares the phases of the two horizontal sync signals, (7) an amplifier that amplifies the phase error signal, (8 ) Is a voltage-controlled oscillator whose control voltage is a voltage corresponding to the phase error signal amplified by the amplifier (7), and whose frequency changes according to this control voltage, (9) is a variable delay line, and (10) is a video signal. It is a processing circuit.

The voltage controlled oscillator (8) controls the delay amount of the variable delay line (9) according to the amplified phase error signal.

Next, the operation will be described. The reproduced FM video signal is input to the FM demodulator (2) and the variable delay line (9), demodulated by the FM demodulator (2), and converted into a baseband video signal. This video signal is a horizontal sync signal extraction circuit (3),
The horizontal synchronizing signal input to (4) and taken out by the horizontal synchronizing signal extracting circuit (3) is input to the phase comparator (6). On the other hand, the horizontal synchronization signal extracted by the horizontal synchronization signal extraction circuit (4) is input to the AFC circuit (5). Figure 3 shows A
In the block diagram of the FC circuit (5), the horizontal synchronizing signal having the horizontal frequency fluctuation input from the horizontal synchronizing signal extraction circuit (4) is input from the frequency divider (53) to the phase comparison circuit (51). The fluctuation of the horizontal frequency is compared with the horizontal sync signal of the average frequency from which the horizontal frequency has been removed, and the phase error signal is sent to the LPF (52) that passes only the ultra-low frequency component. The smoothed output signal of the LPF (52) is input to the voltage controlled oscillator (54), and the output signal is divided by the frequency divider (53) to become a horizontal frequency signal, which is a low-pass signal of the AFC circuit (5). It is input to the phase comparator (6) as a reference horizontal synchronizing signal from which horizontal frequency fluctuations up to the ultra-low frequency band determined by the time constant of the filter have been removed. The phase comparator (6) compares the phases of the horizontal synchronizing signal having a variation and the reference horizontal synchronizing signal, and inputs the phase error signal for each 1H of both signals to the amplifier (7). The amplifier (7) amplifies the phase error signal to a level at which the voltage controlled oscillator (8) can control the variable delay line (9) and inputs the amplified signal to the oscillator (8). 8) inputs a signal for controlling the delay amount of the variable delay line (9) to the delay line (9), and the delay line (9)
Is the playback FM video signal input from the input terminal (1)
The reference horizontal synchronizing signal output from the AFC circuit (5) is controlled so as to synchronize with the reference horizontal synchronizing signal every 1H, and is input to the video signal processing circuit (10). For this reason, the high frequency fluctuation component of the horizontal frequency of the reproduced FM video signal is removed, so that the vertical bending or shaking of the reproduced image is removed.

[Problems to be Solved by the Invention]

The conventional feedforward type FWO-FM-TBC circuit is configured as described above, and the AF that creates the reference horizontal synchronization signal
Since the horizontal sync signal from which the horizontal frequency fluctuation component has not been removed is input to the C circuit, the reference horizontal sync signal output from the AFC circuit contains fluctuations that cannot be completely removed. There was a problem that the vertical bending of the was not removed so much.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain an FM-TBC circuit capable of reducing the vertical bending and shaking of a reproduced image as compared with the conventional one. To do.

[Means for solving the problem]

A magnetic reproducing apparatus according to the present invention comprises a variable delay means for inputting a reproduction FM video signal, a first horizontal synchronization signal extracting means for extracting a first horizontal synchronization signal from a signal obtained by demodulating the reproduction FM video signal, and a variable Second horizontal synchronization signal extraction means for extracting a second horizontal synchronization signal from a signal obtained by demodulating the FM video signal output from the delay means, and reference horizontal synchronization obtained by removing a variation component of the horizontal frequency from the second horizontal synchronization signal. A fluctuation component removing means for outputting a signal, a phase comparing means for comparing the phases of the reference horizontal synchronizing signal and the first horizontal synchronizing signal and outputting a voltage signal of a level corresponding to the phase difference between these, and the voltage signal And a delay amount control means for controlling the delay amount of the variable delay means based on the above, and is configured to synchronize the first horizontal synchronizing signal with the reference horizontal synchronizing signal.

[Action]

In the magnetic reproducing apparatus of the present invention, the reference horizontal synchronizing signal is output by the fluctuation component removing means from the second horizontal synchronizing signal extracted from the signal obtained by demodulating the FM video signal output from the variable delay means. Therefore, the fluctuation component removing unit can also remove the fluctuation amount of the horizontal frequency included in the reference synchronization signal that cannot be conventionally removed. Therefore, the fluctuation component of the horizontal frequency of the FM video signal output from the variable delay means is reduced, and it is possible to effectively remove the vertical shake or bend of the reproduced image.

〔Example〕

FIG. 1 is a block circuit diagram of an embodiment of the present invention.

In the figure, (11) is a second FM demodulator, which FM demodulates the output signal of the variable delay line (9), and the demodulated video signal is input to the horizontal synchronization signal extraction circuit (4) and extracted. Different from the conventional example shown in FIG. 2 in that the horizontal synchronizing signal is input to the AFC circuit (5), the rest of the configuration is the same, and the description thereof is omitted.

Next, the operation of the part different from the conventional example will be described.
The FM video signal output from the variable delay line (9) from which the fluctuation of the horizontal frequency is removed is demodulated by the FM demodulator (11),
Converted to baseband video signal. This video signal is input to the horizontal sync signal extraction circuit (4), the extracted horizontal sync signal is input to the AFC circuit (5), and the ultra low frequency band determined by the time constant of the low-pass filter of the AFC circuit (5). The reference horizontal synchronizing signal from which the fluctuation of the horizontal frequency is removed is input to the phase comparator (6).

On the other hand, the phase comparator (6) has a horizontal synchronization signal extraction circuit (3) for extracting the video signal demodulated by the FM demodulator (2).
The horizontal sync signal extracted in step (4) is input, and the phase error signal having a magnitude proportional to the magnitude of the phase shift from the reference horizontal sync signal input from the AFC circuit (5) is input to the amplifier (7), The amplifier (7) sends a signal obtained by amplifying the phase error signal to the voltage controlled oscillator (8). The voltage controlled oscillator (8) controls the delay amount of the variable delay line (9) in accordance with the amplified phase error signal to generate a reference horizontal synchronizing signal.
The FM video signal is controlled so as to synchronize every 1H.

Therefore, in the reference horizontal synchronizing signal input from the AFC circuit (5) to the phase comparator (6), fluctuations in the high frequency range of the horizontal frequency of the reproduced FM video signal are removed, so that it is better than in the conventional example. Vertical bending and shaking of the reproduced image is reduced.

〔The invention's effect〕

As described above, according to the magnetic reproducing apparatus of the present invention, in the feedforward type FWO-FM-TBC circuit, the FM image with a small fluctuation component of the horizontal frequency passing through the variable delay means in the signal source for generating the reference horizontal synchronizing signal. Since the signal is used, the fluctuation component of the horizontal frequency, which could not be removed conventionally and was included in the reference horizontal sync signal, can also be removed by the variation component removing means, so that the vertical bending or wobbling of the reproduced image is greater than in the past. Will be even less.

[Brief description of drawings]

FIG. 1 is a block diagram of a feedforward type FWO-FM-TBC circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional feedforward type FWO-FM-TBC circuit.
The figure is a block diagram of the AFC circuit. (2), (11) ... FM demodulator, (3), (4) ... horizontal sync signal extraction circuit, (5) ... AFC circuit, (6) ... phase comparator, (8) ... Voltage controlled oscillator, (9) ... Variable delay line. In each figure, the same reference numerals indicate the same or corresponding parts.

Front Page Continuation (72) Inventor Koichi Yamashita No. 1 Baba Institute, Nagaokakyo-shi, Kyoto Inside the Electronic Product Development Laboratory, Mitsubishi Electric Corporation (56) Reference JP-A-55-125780 (JP, A) JP-A-62 -256589 (JP, A) JP-A-62-164269 (JP, A)

Claims (1)

(57) [Claims] 1. A variable delay means for inputting a reproduction FM video signal, a first horizontal synchronization signal extraction means for extracting a first horizontal synchronization signal from a signal obtained by demodulating the reproduction FM video signal, and the variable delay means. Second horizontal synchronizing signal extracting means for extracting a second horizontal synchronizing signal from a signal obtained by modulating the FM video signal outputted from the reference horizontal synchronizing signal obtained by removing the fluctuation component of the horizontal frequency from the second horizontal synchronizing signal. A fluctuation component removing means for outputting, a phase comparing means for comparing the phases of the reference horizontal synchronizing signal and the first horizontal synchronizing signal and outputting a voltage signal of a level corresponding to the phase difference between them, and the voltage signal A delay amount control means for controlling the delay amount of the variable delay means based on the above, and the first horizontal synchronizing signal is synchronized with the reference horizontal synchronizing signal.