JPH04247793A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Field of Application] The present invention relates to magnetic recording and reproducing devices such as video tape recorders, and in particular, a luminance/chrominance signal separation circuit and a frequency band limiting circuit that also serve as filters and delay circuits. The present invention relates to a magnetic recording/reproducing device.

0003

2. Description of the Related Art Many magnetic recording and reproducing devices such as video tape recorders employ a color low range conversion recording method. This color low-pass conversion recording method separates the luminance signal and color signal from the composite video signal CV, passes the color signal through a bandpass filter, frequency-converts the color signal to a low-pass frequency, and converts the luminance signal to a low-pass filter. In this method, the signals are passed through a pass filter, then FM modulated, and then superimposed and recorded on a videotape.

FIG. 2 is a block diagram showing the configuration of a conventional magnetic recording/reproducing device. FIGS. 3(a) and 3(b) are diagrams showing frequency allocation in the above-mentioned color low-pass conversion method.

In FIG. 2, in the input video composite signal CV, as can be seen from FIG. 3(a), the frequency of the color signal is superimposed on a relatively high band of the luminance signal. The composite video signal CV including this color signal and luminance signal is generated by a luminance/luminance signal composed of a comb filter, etc.
The color signal separation circuit 101 separates the signal into a color signal and a luminance signal. The separated color signal is passed through a bandpass filter 1
After the band is limited by 02, the frequency conversion circuit 103
is converted to a lower frequency. The separated luminance signal is filtered through a low-pass filter 104 to pass only low frequencies, and then filtered to the FM
A modulator 105 performs FM modulation. This low-frequency conversion color signal and the FM luminance signal are superimposed in an adder 106 and are
As shown in b), a recording signal is output in which a low frequency conversion color signal is placed on the low frequency side and an FM luminance signal is placed on the slightly higher frequency side.

[0006] The reason why the color signal and the luminance signal are used through a filter in the magnetic recording/reproducing device is that the low-frequency conversion color signal and the FM luminance signal need to be band-separated so that they do not interfere with each other.

[0007] In such a magnetic recording/reproducing device,
A luminance/chrominance signal separation circuit is required to separate the luminance signal and chrominance signal from the composite video signal CV.

FIG. 4 is a block diagram showing an example of the configuration of a conventional luminance/chrominance signal separation circuit using a comb filter.

The input composite video signal is 1
The color signals are separated by a comb filter composed of an H delay line 1011 and a subtracter 1012. However, as it is, since signals outside the color signal band are also included, only the color signal band components are extracted by passing through a bandpass filter (BPF) 1013 and used as a color signal. This color signal is input to subtracter 1014. Since the composite video signal passed through the delay circuit 1015 is input to the subtracter 1014, a luminance signal can be obtained by subtracting the color signal from this composite video signal. Note that the reason for providing the delay circuit 1015 is that the color signal is
Since the phase and group delay shift when passing through the composite video signal CV 1015, the composite video signal CV is passed through a delay circuit 1015 in order to correct this.

In the conventional magnetic recording/reproducing device described above, the color signal is passed twice through a bandpass filter 1013 in the luminance/chrominance signal separation circuit and a bandpass filter 102 for limiting the frequency band. The signal is passed through a delay circuit 1015 of a luminance/chrominance signal separation circuit and a low-pass filter 104 for frequency band limitation.

The filters and delay circuits described above are expensive components, and using a plurality of them increases the number of components, lowering reliability and complicating the circuit.

0012

[Problems to be Solved by the Invention] In the above-mentioned conventional magnetic recording/reproducing device and luminance/chrominance signal separation circuit, multiple filters and delay circuits are used, increasing the number of parts and increasing the cost of the circuit. However, there is a problem that the circuit becomes complicated and reliability is lowered.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a magnetic recording/reproducing device which also serves as a filter and a delay circuit, reducing costs and simplifying the circuit. do.

[Configuration of the invention]

[0015]

Means for Solving the Problems The present invention provides a comb that delays a composite video signal by one horizontal period delay circuit, and obtains a color signal by subtracting the delayed composite video signal and the original composite video signal by a subtracter. a band-pass filter that extracts color signal components from the color signal from the comb-shaped filter and limits the frequency band; and a low-pass filter that extracts the low-frequency components of the composite video signal and limits the frequency band. , a subtracter that obtains a luminance signal by subtracting the color signal passed through the band-pass filter from the signal from the low-pass filter, and an FM modulator that performs FM modulation on this luminance signal.
The present invention is characterized by comprising a frequency conversion circuit that converts the color signal from the band-pass filter into a low frequency band.

[0016]

[Function] With the above configuration, it can be used both as a band-pass filter that extracts only the color signal component and as a band-pass filter that limits the frequency band, and also as a low-pass filter that extracts the low-frequency component of the luminance signal and as a band-pass filter that limits the frequency band. It can also be used as a limiting low-pass filter, and can be used as one low-pass filter.
Only one bandpass filter is required.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the illustrated embodiments. FIG. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention.

In FIG. 1, the input composite signal CV
is input to the 1H delay circuit 1 and the subtracter 2, and is also input to the low-pass filter (LPF) 3. The output signal of the subtracter 2 is input to a phase correction circuit 5 and a frequency conversion circuit 6 through a band pass filter (BPF) 4. The composite video signal CV contains only low-frequency components by LPF3. The composite signal passed through the LPF 3 and the color signal passed through the phase correction circuit 5 are separated by a subtracter 7.
is input. The subtracter 7 subtracts the color signal from the composite signal to obtain a luminance signal and output it. The luminance signal from the subtracter 7 is input to the FM modulator 8. FM modulator 8 supplies an FM luminance signal obtained by FM modulating the luminance signal to adder 9 . Further, the frequency conversion circuit 6 supplies the adder 9 with a low-frequency converted color signal obtained by low-frequency conversion of the color signal. Thereby, a recording signal is obtained from the output of the adder 9.

The operation of the embodiment thus constructed will be explained below. The composite video signal CV is subtracted by a subtracter 2 from the signal passed through the 1H delay circuit 1 and separated into color signals. This color signal is passed through the BPF 4 to only the color signal band components, and is limited to the band of the recording color signal. This color signal is led to a frequency conversion circuit 6, where it becomes a low frequency converted color signal and is applied to an adder 9.

On the other hand, the composite video signal CV is
The signal is band-limited to the band of the recording luminance signal by the PF 3 and guided to the subtracter 7 . This composite video signal CV is subtracted by a subtracter 7 from the color signal passed through the phase correction circuit 5 to remove the color signal. This results in a luminance signal whose band is limited to the band of the recorded luminance signal, and is introduced into the FM modulator 8. The FM modulator 8 performs FM modulation on the luminance signal to produce an FM luminance signal, which is then supplied to an adder 9 where it is superimposed on the low-frequency conversion color signal to become a recording signal. Note that the phase correction circuit 5 is for matching the group delay and phase between the BPF 4 of the chrominance signal and the LPF 3 of the luminance signal, and may be unnecessary in some cases.

[0021]

As explained above, according to the present invention, by using a filter and a delay circuit for both luminance/color separation and frequency band limitation, the number of parts can be reduced and costs can be reduced. Moreover, there is an excellent effect that the circuit can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording/reproducing apparatus of the present invention.

FIG. 2 is a block diagram showing a conventional magnetic recording/reproducing device.

FIG. 3 is a diagram showing frequency allocation in a color low-band conversion recording method.

FIG. 4 is a block diagram showing a conventional luminance/color signal separation circuit.

[Explanation of symbols]

1...1H delay circuit 2, 7...Subtractor 3...LPF 4...BPF 5...Phase correction circuit 6...Frequency conversion circuit 8...FM modulator 9... Adder

Claims (1)

[Claims] 1. A comb filter which obtains a color signal by delaying a composite video signal by one horizontal period delay circuit and subtracting the delayed composite video signal and the original composite video signal by a subtracter, and the comb filter. a band-pass filter that extracts color signal components from the color signal from the composite video signal and limits the frequency band; a low-pass filter that extracts the low-frequency components of the composite video signal and limits the frequency band; a subtracter that obtains a luminance signal by subtracting the chrominance signal passed through the band-pass filter from the signal; an FM modulator that performs FM modulation on the luminance signal from the subtracter; and a low-frequency converter for the chrominance signal from the band-pass filter. 1. A magnetic recording/reproducing device comprising: a frequency converting circuit.