JPH03119888A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reproduce a chrominance signal with fidelity by providing a non-linear amplifying means in a reproducing system, amplifying the signal while the more enlarging the amplification factor, the more the amplitude level of an input low area converting chrominance signal is high, and correcting the amplitude limit of the input low area converting chrominance signal. CONSTITUTION:A chrominance signal processing circuit 4 converts the frequency of the inputted low area converting chrominance signal to the chrominance signal of a base band and afterwards, cross talk removal, etc., is executed. Then, the processed chrominance signal of the base band is outputted to a non-linear amplifier circuit 5. The non-linear amplifier circuit 5 amplifies the chrominance signal of the base band to be inputted while enlarging the amplification factor for a part, where the amplitude level is made high, rather than the other part and afterwards, this chrominance signal is outputted to an adder 6. At such a time, the reproducing chrominance signal receiving the amplitude limit by a non-linear electromagnetic converting property passing through a magnetic type is inserted to the non-linear amplifier circuit 5. Thus, the amplitude limit is corrected and a linear relationship can be obtained between the chrominance signal at recording time and the chrominance signal at reproducing time. Then, the chrominance signal can be reproduced with fidelity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording/reproducing device, and particularly to amplitude correction processing of a color signal during reproduction.

(Prior Art) Conventionally, for example, a VH3 system video tape recorder (VT
R), when recording, the color signal is low-frequency converted, and the luminance signal is FM-modulated, and then the low-frequency converted color signal is superimposed on this modulated luminance signal, and the FM signal is used as a bias, thereby producing a magnetic tape. It is recorded in In this conventional recording method, as shown in Figure 4, the color signal is fixed at FM.
Since the signal is superimposed from the bias point, it has an amplitude limiting characteristic due to the nonlinear characteristics of the magnetic tape as shown in C in the figure. For this reason, when the color signals recorded on the magnetic tape are reproduced, there is a problem in that the reproduction level of the portions with high color density becomes relatively low compared to that at the time of recording.

Here, the color signal a is recorded on the tape as shown in FIG. Therefore, during playback, an FM composite signal as shown in d is obtained. When the color signal is separated from this FM composite signal, it becomes as shown in e. This separated color signal e has an amplitude at a bay relative to the recorded color signal a. Therefore, if the recorded color signal a is input and the reproduced color signal e is output, the input/output characteristics will have the characteristics shown in FIG.

(Problems to be Solved by the Invention) As mentioned above, in conventional VTRs, due to the electromagnetic nonlinear characteristics of the magnetic tape, the reproduced color signal reproduced from the magnetic tape is limited in amplitude relative to the recorded color signal. However, it is not possible to obtain a faithful reproduced color signal, which has the drawback of impairing faithful color expression on the reproduced screen.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a magnetic recording and reproducing apparatus capable of reproducing faithful color signals with good linearity from a tape with respect to recorded color signals.

[Structure of the invention]

(Means for Solving the Problems) The present invention separates a modulated luminance signal and a low frequency conversion color signal from a reproduced signal obtained by scanning a magnetic tape with a head, and then
In a magnetic recording/reproducing device that demodulates a luminance signal and frequency-converts a low-frequency converted color signal into a baseband color signal, and then mixes both signals to create a reproduced video signal, the higher the amplitude level of the input signal, the more A nonlinear amplification means with a large amplification factor is provided, and the low-pass conversion color signal is amplified by the nonlinear amplification means and then mixed with the demodulated luminance signal.

(Function) In the magnetic recording and reproducing apparatus of the present invention, the nonlinear amplifying means provided in the reproducing system amplifies the input low-frequency conversion color signal by increasing its amplification factor as the amplitude level of the signal increases. Therefore, the nonlinear amplification means corrects the amplitude limitation of the input low-pass converted color signal.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a reproducing system of a magnetic recording/reproducing apparatus according to the present invention. 1 is an amplifier circuit that amplifies the FM composite signal including the color signal reproduced by the reproduction head 7;
2 is a signal separation circuit that separates the FMff degree signal and the low frequency conversion color signal from the FM composite signal; 3 is the luminance signal processing circuit that performs processing such as decoding the FM''f1 degree signal; and 4 is the low frequency conversion color signal. Convert the frequency to a baseband color signal,
a color signal processing circuit that removes crosstalk, etc.; 5 a nonlinear amplification circuit that nonlinearly amplifies the baseband color signal; 6;
An adder mixes the luminance signal output from the luminance signal processing circuit 3 and the chrominance signal output from the nonlinear amplifier circuit 5 to produce a video signal, and 7 is a playback head that reproduces the video signal from the tape.

Here, the nonlinear amplification circuit 5 constitutes nonlinear amplification means.

Next, the operation of this embodiment will be explained. The reproduced FM composite signal obtained by scanning a tape (not shown) with the reproduction head 7 is amplified by the amplifier circuit 1, and then separated into an FM luminance signal and a low-frequency conversion color signal by the signal separation port B2, and each is subjected to luminance signal processing. Circuit 3 and color signal processing diagram H! It is input to lI4. The color signal processing circuit 4 converts the frequency of the input low-pass conversion color signal to a baseband color signal, performs crosstalk removal, etc., and sends the processed baseband color signal to the nonlinear amplifier circuit 5. Output. Since the nonlinear amplifier circuit 5 has the characteristics shown in FIG. This color signal is output to adder 6.

On the other hand, the luminance signal processing circuit 3 demodulates the input FM luminance signal and outputs this demodulated luminance signal to the adder 6. The adder 6 mixes the input luminance signal and color signal to create a video signal, and outputs this to the next stage.

FIG. 2 is a circuit diagram showing a specific example of the nonlinear amplifier circuit 5 shown in FIG. In this example, a parallel circuit of two diodes D connected with opposite polarities is connected to the emitter of the transistor T via a capacitor C1 and a resistor R3, so the input/output characteristics between the base and collector of the transistor T are The result is as shown in FIG. 5C. Therefore, by inputting the color signal output from the color signal processing circuit 4 shown in FIG. 1 to the base of the transistor T, a color signal whose amplitude limitation has been corrected can be taken out from the collector. Note that the resistor R1 and the resistor R2 are the collector resistance and emitter resistance of the transistor T, respectively.

According to this embodiment, the amplitude limitation is corrected by passing the reproduced color signal, which has been amplitude limited due to the nonlinear electromagnetic conversion characteristics via the magnetic tape, through the nonlinear amplifier circuit 5, so that the amplitude limitation is corrected as shown in FIG. Thus, it is possible to create a linear relationship between the color signal during recording and the color signal during playback, making it possible to faithfully reproduce the color signal.

〔Effect of the invention〕

As described above, according to the magnetic recording and reproducing apparatus of the present invention,
A faithful color signal with good linearity can be reproduced from the tape with respect to the recorded color signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the reproducing system of the magnetic recording/reproducing apparatus of the present invention, FIG. 2 is a circuit diagram showing a specific example of the nonlinear amplification circuit shown in FIG. 1, and FIG. Fig. 1 is a characteristic diagram showing the relationship between the recorded color signal and the reproduced color signal when passing through the reproduction system shown in Fig. 1; Fig. 4 is a diagram showing an example of electromagnetic conversion characteristics of the color signal for magnetic tape; The figure shows the relationship between the conventional recorded color signal and reproduced color signal and an example of the amplification characteristics of the nonlinear amplifier circuit shown in FIG. 1. 1... Amplification circuit 2... Signal separation circuit 3... Luminance signal processing circuit 4... Color signal processing circuit 5... Nonlinear amplifier circuit 6... Adder 7... Reproduction head

Claims (1)

[Claims] After separating a modulated luminance signal and a low-frequency converted color signal from the reproduced signal obtained by scanning the magnetic tape with a head, the luminance signal is demodulated and the low-frequency converted color signal is frequency-converted to a baseband color signal. In a magnetic recording and reproducing apparatus that mixes both signals after the input signal is processed, a nonlinear amplification means is provided in which the amplification factor increases as the amplitude level of the input signal increases, and the low frequency conversion color signal is A magnetic recording/reproducing device characterized in that the magnetic recording/reproducing device amplifies the signal and then mixes the signal with the demodulated luminance signal.