JPH0738922A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the S/N of a recovered chrominance signal by varying band limit according to a phase shift fluctuation component by a band limit variable means when the reproduced chrominance signal is band-limited so as to allow a PLL to be hardly unlocked thereby reducing the phase shift fluctuation. CONSTITUTION:In the magnetic recording and reproducing device which frequency-modulates a luminance signal, applies low frequency conversion to a chrominance signal, mixes and records/reproduces the luminance signal and the chrominance signal, a reproduced chrominance signal enters a variable band pass filter BPF 9, in which band-limit is executed and the result enters an automatic chroma control circuit ACC 2. The ACC 2 makes a color signal level constant, a frequency converter 3 makes frequency conversion and a BPF 4 implements band limit. The phase of the output of the BPF 4 and the phase of the crystal vibrator 8 are compared and its resulting output is fed to a VCO 6 and a detector 10. The output of the VCO 6 is used and a synchronizing separator circuit makes synchronization separation and the result is fed back to the frequency converter 3. On the other hand, the detector 10 detects a phase shift fluctuation and its output varies the band limit width of the BPF 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a magnetic recording / reproducing apparatus for frequency-modulating a luminance signal, converting a chrominance signal into a low frequency range, and mixing and recording.

[0002]

2. Description of the Related Art Conventionally, a magnetic recording / reproducing apparatus frequency-modulates a luminance signal, converts a chrominance signal into a low frequency range, mixes and records the signal, and performs reproduction by performing constant band limitation of a reproduced color signal.
FIG. 2 is a block diagram showing processing of reproduced color signals in the conventional magnetic recording apparatus.

In FIG. 2, 1 is a band pass filter for limiting the band (hereinafter referred to as BPF), 2 is an auto-chromatographic control circuit (hereinafter referred to as ACC) that keeps a color signal level constant, and 3 is a frequency. The frequency converters 4 and 4 are band pass filters (B.P.
F) 5 is a phase comparator for phase comparison, 6 is a voltage controlled oscillator (VCO), 7 is a sync separator for performing sync separation, and 8 is a crystal oscillator (X'Tal) for phase comparison with the phase comparator 5.
Is.

Next, the operation of the conventional example will be described with reference to FIG. In FIG. 2, the reproduced color signal is B. P. Enter F1 to limit the band, enter ACC2 to make the color signal level constant, frequency-convert by the frequency converter 3, P. The band is limited after entering F4, and the output thereof is phase-compared with X'Tal 8 by the phase comparator 5 and output to the VCO 6. The output of the VCO 6 is used to perform the sync separation by the sync separator 7, and the frequency converter 7
Return to.

[0005]

As described above, in the above-mentioned conventional example, when the reproduction color signal is band-limited, the reproduction color signal is band-limited, so that the reproduction color is reproduced when a bad tape is reproduced. When the band limitation of the signal is constant, a signal with a large amount of phase shift fluctuation may lose the lock of the phase lock loop (hereinafter referred to as PLL) and becomes a signal with a large phase shift fluctuation component. However, there was a problem that the S / N of No. 1 deteriorated.

The present invention has been made in order to solve the above-mentioned problems, and the band limitation of the reproduced color signal is varied by the amount of phase shift variation to make it difficult for the PLL to be out of lock and to reduce the phase shift variation. However, the object is to improve the S / N of the reproduced color signal.

[0007]

Therefore, according to the present invention, a magnetic recording in which the luminance signal is frequency-modulated, the color signal is converted to a low frequency, and the luminance signal and the color signal are mixed and recorded / reproduced. In the reproducing apparatus, when the reproduction color signal is band-limited, a magnetic recording / reproducing apparatus including a band limitation changing unit that changes the band limitation according to a phase shift variation is intended to achieve the above object. is there.

[0008]

In the magnetic recording / reproducing apparatus of the present invention, when the reproduction color signal is band-limited, the band limiting variable means changes the band limitation in accordance with the phase shift variation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing processing of reproduced color signals of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In the figure,
The same reference numerals as those of the conventional example indicate the same or corresponding portions, and the duplicated description thereof will be omitted.

In FIG. 1, reference numeral A is a band limitation variable means, which is composed of a variable bandpass filter 9 and a detector 10, and which, when band limiting the reproduced color signal, changes the band limitation by the phase shift variation. Is.

Further, FIG. 1 showing this embodiment differs from FIG. 2 showing the above-mentioned conventional example in that a detector 10 for detecting a phase shift variation is provided after the phase comparator 5, and B. P. The F1 is a variable bandpass filter 9, and other configurations are the same as those of the conventional example.

Next, the operation of this embodiment will be described with reference to FIG. In FIG. 1, a reproduction color signal is input to the variable bandpass filter 9, band limitation is performed, and the variable color bandpass filter 9 enters ACC2. AC
At C2, the color signal level is kept constant, the frequency converter 3 is entered, and the frequency is converted. P. Bandwidth is limited by F4. And
The output is phase-compared with the crystal oscillator (X′Tal) 8 and the phase comparator 5, and the output is input to the VCO 6 and the detector 10. The output of the VCO 6 is used to perform the sync separation in the sync separator 7, and the frequency is returned to the frequency converter 3. On the other hand, the detector 1
At 0, the phase shift fluctuation detection is performed, and the band limiting width of the variable bandpass filter 9 is changed by the output.

As described above, in this embodiment, when the reproduced color signal having a large amount of phase shift variation is reproduced, the band limitation is changed in accordance with the amount of phase shift variation, thereby reducing the amount of phase shift variation. The S / N of the reproduced color signal is improved.

[0014]

As described above, according to the present invention, by changing the band limitation of the reproduced color signal according to the phase shift variation, it becomes difficult for the PLL to be unlocked, the phase shift variation is small, and the reproduced color is reduced. The signal S / N is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing processing of a reproduction color signal of a magnetic recording / reproducing apparatus which is an embodiment of the present invention.

FIG. 2 is a configuration diagram showing processing of a reproduction color signal of a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 A band limiting variable means 1 B. P. F 2 ACC 3 frequency converter 4 B. P. F 5 phase comparator 6 VCO 7 sync separator 8 X'Tal 9 variable bandpass filter (variable BPF) In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus that frequency-modulates a luminance signal, converts a color signal into a low-frequency range, and records / reproduces the luminance signal and the color signal by mixing. In addition, the magnetic recording / reproducing apparatus is characterized by comprising a band limitation changing means for changing the band limitation according to a phase shift variation.