JPH0591539A - Recording circuit for color video signal - Google Patents

Abstract

PURPOSE:To furthermore improve the quantity of reproduced sound by connecting a trap circuit having trap frequency levels equal to respective center frequency levels of an FM main sound signal and an FM sub-sound signal to a communication line for a low band conversion carrier chrominance signal. CONSTITUTION:In a color video signal recording circuit for mixing an FM brightness signal, a low band conversion carrier chrominance signal and FM main and sub sound signals, supplying the mixed signal to a recording means (rotary magnetic head) 13 and recording the mixed signal in a recording medium, the trap circuit 9 having trap frequency levels equal to respective center frequency levels of the FM main and sub sound signals is connected to the low band conversion carrier chrominance signal transmission line. Since frequency components corresponding to the FM main and sub sound signals in the low band conversion carrier chrominance signal can sufficiently be reduced, interference to the FM main and sub sound signals corresponding to the frequency components can surely be blocked. Consequently reproduced sound quality (sound quality for streophonic and monophonic reproducing, especially for streophonic reproducing) can furthermore be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR color video signal recording circuit.

[0002]

2. Description of the Related Art In a recording circuit of 8 mm VTR, an FM luminance signal, a low frequency conversion carrier color signal and an FM main and sub audio signal are mixed and supplied to a rotary magnetic head for recording on a magnetic tape. However, conventionally, as shown in FIG.
A trap circuit having a trap frequency Ft equal to an intermediate frequency between the center frequencies Fm and Fs of the M main and sub audio signals is provided in the transmission path of the low-frequency conversion carrier chrominance signal to correspond to the FM main and sub audio signals. The frequency component is reduced to reduce the interference of the frequency component of the low-frequency conversion carrier color signal with the FM main and sub audio signals.

[0003]

However, the trap circuit in the recording circuit of the conventional VTR cannot sufficiently reduce the frequency components corresponding to the FM main and sub audio signals in the low frequency conversion carrier color signal. Therefore, when the FM main and sub audio signals are demodulated during reproduction and stereo or monaural reproduction is performed, the reproduced sound quality cannot be said to be sufficiently good. This becomes a problem particularly when the low-pass conversion carrier color signal is broadened.

In view of the above point, a recording circuit for a color video signal, which mixes an FM luminance signal, a low-frequency conversion carrier color signal, and FM main and sub audio signals and supplies them to a recording means to record them on a recording medium. In the above, an attempt is made to propose one that can further improve the reproduction sound quality.

[0005]

According to the present invention, an FM luminance signal, a low frequency conversion carrier color signal and an FM main and sub audio signal are mixed and supplied to a recording means 13 for recording on a recording medium. In the color video signal recording circuit, a trap circuit 9 having a trap frequency equal to the center frequency of each of the FM main and sub audio signals is provided on the transmission path of the low-frequency conversion carrier color signal.

[0006]

According to the present invention, the frequency components corresponding to the FM main and sub audio signals in the low-frequency conversion carrier color signal can be sufficiently reduced, so that the interference of the frequency components with the FM main and sub audio signals can be surely performed. It can be prevented, and the reproduced sound quality can be further improved.

[0007]

EXAMPLE An example in which the present invention is applied to an 8 mm VTR will be described in detail below. First, the circuit configuration of the recording circuit will be described with reference to FIG. The color video signal from the input terminal 1 is supplied to the luminance / chromaticity separation circuit 4 and separated into a luminance signal Y and a carrier color signal C. The luminance signal Y is supplied to the FM modulation circuit 5 and frequency-modulated, and then supplied to the frequency component reducing half trap circuit 7 corresponding to the FM sound or the low-frequency conversion carrier color signal. The carrier color signal C is supplied to the low frequency conversion circuit 6 and converted into a low frequency band, and the low frequency conversion carrier color signal C ′ is passed through an ACC (automatic color saturation adjustment) circuit 8 to a frequency component corresponding to the FM audio signal. It is supplied to the reduction trap circuit 9. The low-frequency conversion carrier color signal C'from the trap circuit 9 and the FM audio signal FM from the input terminal 2
-A and automatic tracking adjustment signal A from input terminal 3
TF and TF are supplied to the adder 11 to be added. Adder 1
The addition output of 1 and the FM luminance signal FM-Y from the half trap circuit 7 are supplied to the adder 10 and added,
The added output is supplied to the pair of rotary magnetic heads 13 through the recording amplifier 12 and recorded so as to form inclined tracks on the magnetic tape.

Next, with reference to FIG. 2, a specific circuit configuration of the trap circuit 9 of FIG. 1 will be described. 15 is an input terminal, 2
0 is an output terminal. Between the input / output terminals 15 and 20, a circuit 16 for increasing the Q of the trap, a trap circuit 17 for frequency component reduction corresponding to an FM audio signal, a low-pass filter 18 for frequency component reduction corresponding to a luminance signal, and a buffer amplifier 19, They are connected in cascade.

The circuit 16 for increasing the Q is formed by inserting a parallel circuit of a resistor 21 and a capacitor 22 and a series circuit of a coil 23 in series with the transmission line.

The trap circuit 17 includes a series circuit of a capacitor 24 and a coil 26, a capacitor 25 and a coil 2.
7 series circuits are respectively connected in parallel to the transmission lines. The trap circuit 17, as shown in FIG. 3, has a center frequency F of the FM main and sub audio signals sandwiched between both bands of the low frequency conversion carrier color signal and the FM luminance signal.
This is a twin trap circuit having a trap frequency Ftm (resonance frequency of a series resonance circuit including a capacitor 24 and a coil 26) and a trap frequency FMts (resonance frequency of series resonance circuit including a capacitor 25 and a coil 27) that are equal to m and Fs, respectively. ..

The low-pass filter 18 is constructed by connecting a series circuit of a resistor 28 and a capacitor 29, and a capacitor 30 in parallel to the transmission line.

When the recording means is a magnetic head, the recording medium may be a magnetic disk. The recording means and the recording medium may be other recording means and recording medium such as an optical magnetic head and an optical disk (optical sheet), respectively.

[0013]

According to the present invention described above, an FM luminance signal, a low-frequency conversion carrier color signal, and an FM main and sub audio signal are mixed and supplied to a recording means for recording on a recording medium. Playback sound quality (stereo and monaural, especially stereo playback sound quality) in the video signal recording circuit
Can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a recording circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of a trap circuit of the recording circuit.

FIG. 3 is an explanatory diagram of a trap frequency of the trap circuit of the embodiment.

FIG. 4 is an explanatory diagram of a trap frequency of a conventional trap circuit.

[Explanation of symbols]

 9 Trap circuit 13 Rotating magnetic head

Claims (1)

[Claims] 1. A color video signal recording circuit adapted to mix an FM luminance signal, a low-frequency conversion carrier color signal, and FM main and sub audio signals and supply them to a recording means for recording on a recording medium. A recording circuit for a color video signal, characterized in that a trap circuit having a trap frequency equal to each center frequency of the FM main and sub audio signals is provided on the transmission path of the low-frequency conversion carrier color signal.