JPH02104192A - Magnetic recorder - Google Patents

Abstract

PURPOSE:To attain recording/reproducing with high picture quality by modulating the frequency of a brightness signal to which a beat cancel signal is added, adding and composing the frequency-converted signal to a low band-converted carrier chrominance signal and multiplexedly recording the signals on the same track. CONSTITUTION:A composite color video signal SIN is separated into a brightness signal Y and a carrier chrominance signal C by an Y/C separating circuit 11, the signal C is color-corrected by an automatic color correcting circuit 12 and applied to a frequency converter 13 and the signal Y is applied to a signal adder 23 from a signal changing switch 21 through a clamp circuit 22. A beat cancel signal having twice the frequency of a chrominance subcarrier is formed from the signal C by a beat cancel signal forming circuit 17 and added to the brightness signal by the signal adder 23. The frequency of the added brightness signal Y is modulated and the frequency-modulated signal is added to a low band-converted carrier chrominance signal and multiplexedly recorded. Consequently, recording/reproducing with high picture quality can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a magnetic recording device that adds and synthesizes a low-frequency-converted carrier color signal and a frequency-modulated luminance signal and records them on the same track.

B. Summary of the Invention The present invention provides a magnetic recording device that adds and combines a low-band-converted carrier color signal and a frequency-modulated luminance signal and records them on the same track. A beat cancellation signal forming circuit that forms a beat cancellation signal with a side wave number twice the frequency and a signal addition circuit that adds the beat cancellation signal to the frequency modulated luminance signal are provided, and the addition of the beat cancellation signal is performed. By frequency-modulating the brightness signal, adding and combining it with the low-frequency converted carrier color signal, and multiplexing it on the same track, the brightness signal and color signal caused by third-order distortion in the magnetoelectric conversion system can be combined. The secondary beat component is canceled in advance in the recording system to enable high-quality recording and reproduction.

C. Conventional technology Conventionally, color video tape recorders (VTRs) have been used to record and reproduce color video signals using magnetic tape as a recording medium.
), the color video signal is directly frequency-modulated gFl (FM:
In addition to the direct FM recording method in which the color subcarrier frequency is low-converted to a low frequency that is easy to handle, there is so-called chroma low-conversion recording in which the carrier color signal is recorded on the same track along with the luminance signal. As a method, there is a method in which a carrier color signal whose color subcarrier frequency is low band converted is mixed with a luminance signal and then frequency modulated and recorded, and a method in which the color subcarrier frequency is frequency modulated with a carrier color signal whose color subcarrier frequency is low band converted. A method has been adopted in which multiplex recording is performed by adding and synthesizing the luminance signals.

Additionally, the magnetoelectric conversion systems of magnetic tapes, magnetic heads, etc. generally have third-order distortion, and as mentioned above, the carrier color signal whose color subcarrier frequency has been low-band converted and the frequency-modulated luminance signal are added together and synthesized. In VTRs that employ a method of multiplex recording on the same track, diagonal beats occur on the playback screen due to secondary beat components of the carrier color signal and luminance signal caused by the third-order distortion of the magnetoelectric conversion system. However, it is known that image quality deteriorates.

That is, as shown in FIG. 4A, for example, a carrier color signal CL whose color subcarrier frequency is low-pass converted is fc and a frequency-modulated luminance signal Y whose carrier frequency is fv are added and combined and sent to the same trunk. When multiple recording is performed using a magneto-electric conversion system, the playback output reproduced from the track by the magneto-electric conversion system has the following characteristics as shown in FIG.
As shown in , a frequency component of fv±2·fc is generated as a secondary beat component of the carrier color signal CL and the luminance signal YFM, and by demodulating the original luminance signal Y from the luminance signal YF, As shown in FIG. 4C, the secondary beat component of the frequency 2·fc is demodulated and appears as a diagonal beat on the playback screen.

Therefore, in a VTR that employs the multiplex recording method described above, N
As in the TSC method and the conventional examples shown in FIGS. 5 and 6, the demodulated luminance is The secondary beat component included in the signal is extracted, the level of the secondary beat component is controlled by the envelope of the chrominance signal to form a beat cancellation signal, and the secondary beat component included in the luminance signal is canceled out from the above beat. Signal processing for canceling was performed using the cancel signal.

That is, in the conventional example shown in FIG. 5, the luminance signal Y demodulated in the reproduction system is supplied to the first signal synthesizer (52) directly from the signal input terminal (50) and via the IH delay circuit (51). ), and the luminance signal Y is sent to a delay circuit (53
), the first signal synthesizer (52) converts the luminance signal Y and the IH delayed luminance signal YD by the IH delay circuit (51).
The secondary beat component contained in the luminance signal Y is extracted by performing subtractive synthesis with L, and this subtractive synthesis output signal is passed through a bandpass filter (55) and a limiter (
56), the second signal synthesizer (5) as the beat cancellation signal 5alt via the level adjustment circuit (57).
4), and in this second signal synthesis ff1W (54), the beat cancellation signal See is added to and synthesized with the luminance signal Y whose timing has been matched by the delay circuit (53), thereby adding and synthesizing the beat cancellation signal See to the luminance signal Y. A brightness signal Y that has undergone beat cancellation processing by performing a transmitter process to cancel the included secondary beat components using the beat cancellation signal. 1. was output from the signal output terminal (60). Note that the level adjustment circuit (57) receives the color signal C reproduced in this reproduction system through a signal input terminal (58).
), which detects the secondary beat component included in the luminance signal Y by the detection output from the envelope detection circuit (59) provided by the first signal synthesizer (52). A level adjustment operation is performed according to the envelope of the signal C.

In addition, in the conventional example shown in Fig. 5 above, where the color signal component is large and there is no H correlation of the luminance signal, the luminance signal is averaged between H, so the small amplitude part of the luminance signal becomes blurred and the vertical The problem is that resolution is lost.

Further, the conventional example shown in FIG. 6 is a vertical decorrelation detector that detects vertical decorrelation in the subtractive synthesis output signal from the first signal synthesizer (52) in the conventional example shown in FIG. 5. (61) and this vertical decorrelation detector (61)
The level adjustment circuit (57) is determined by the logical product of the detection output by the encoder and the detection output by the enherobe detection circuit (59).
), and a horizontal correlator (63) that performs horizontal correlation processing on the output of the level adjustment circuit (57). Taking the half-wavelength (2/λ) correlation of 2
By actively canceling the conspicuous large-area portion of the next beat, it is possible to prevent the small amplitude portion of the luminance signal from becoming blurred and losing vertical resolution.

D. Problem to be Solved by the Invention By the way, as mentioned above, by utilizing the fact that the color signal and the luminance signal in the NTSC system vision signal are interleaved, the chrominance signal and the luminance signal contained in the demodulated luminance signal are A signal that extracts the next beat component, controls the level of the second beat component using the envelope of the color signal to form a beat cancel signal, and cancels the second beat component included in the luminance signal with the beat cancel signal. Conventional multi-recording VTRs, in which processing is performed in the luminance signal reproduction system, have a problem in that the circuit configuration of the reproduction system is complex, and the small amplitude portion of the luminance signal becomes blurred, resulting in a loss of vertical resolution. In addition, vertical decorrelation detection processing is performed to extract the secondary beat component contained in the luminance signal demodulated in the reproduction system, to prevent the above-mentioned deterioration of vertical resolution. , the above-mentioned non-correlation detection process requires complex signal processing, and there is a risk that the original luminance signal may be degraded by error components in this signal processing circuit.

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned conventional problems by using a simple circuit to convert the secondary beat components of the luminance signal and chrominance signal caused by the third-order distortion of the magneto-electric conversion system in a multi-recording VTR. The purpose is to efficiently cancel the configuration and perform high-quality recording and playback.
The present invention provides a magnetic recording device with a novel configuration in which the secondary beat component is canceled in advance in the recording system.

Means for Solving Problem E1 In order to achieve the above-mentioned object, the present invention provides a magnetic recording device that adds and synthesizes a low-frequency converted carrier color signal and a frequency-modulated luminance signal and records them on the same track. , a beat cancellation signal forming circuit for forming a beat cancellation signal having a frequency twice the color subcarrier frequency from the low-pass converted carrier color signal, and a signal addition circuit for adding the beat cancellation signal to the luminance signal, The luminance signal added with the beat cancellation signal is frequency modulated,
It is characterized in that it is added and synthesized with a low-frequency converted carrier color signal and multiplexed on the same track.

F Function In the magnetic recording device according to the present invention, in the recording system, a beat cancel signal having a frequency twice the color subcarrier frequency is formed from the low frequency converted carrier color signal in a beat cancel signal forming circuit, and the signal addition is performed. A circuit adds the beat cancellation signal to the luminance signal, frequency-modulates the luminance signal to which the beat cancellation signal has been added, and adds and synthesizes it with the low-frequency converted carrier color signal, thereby generating the third order of the magnetoelectric conversion system. Multiplex recording is performed on the same track in a state in which secondary beat components of a luminance signal and a color signal caused by distortion are canceled in advance in a recording system.

G. Example Hereinafter, an example of the magnetic recording device according to the present invention will be described.
This will be explained in detail according to the drawings.

In the embodiment shown in the block diagram of FIG. 1, the composite color video signal SIN to be recorded is transmitted from the first signal input terminal (lO) for composite input to the Y/C separation circuit (
11), and in this Y/C separation circuit (11), the luminance signal Y and the color subcarrier frequency fsc are 3.58MHz.
The carrier color signal C is color-corrected in an automatic color correction circuit (12) and then given to a frequency conversion circuit (13), and the luminance signal Y is sent to a signal changeover switch (12). 21) to a signal addition circuit (23) via a clamp circuit (22).

The frequency conversion circuit (13) is a local oscillation circuit (14)
A local oscillation signal with a frequency fLO of 4.27M)lz is supplied, and this local oscillation signal and the carrier color signal C are frequency-mixed, and the local oscillation signal and the carrier color signal are mixed through a low-pass filter (14). By extracting the difference frequency component from the signal C, frequency conversion processing is performed to convert the color subcarrier frequency fs,c of 3.58 MHz of the carrier color signal C to a low frequency re of 688 KHz.

The low-pass converted carrier color signal CFL taken out from the frequency conversion circuit (13) via the low-pass filter (14) is sent from the signal switching switch (15) via a variable resistor (16) for level adjustment. The signal is supplied to a beat cancel signal forming circuit (17) and a recording amplification circuit (18), amplified by the recording amplification circuit (18), and provided to a signal synthesis circuit (30).

The beat cancel signal forming circuit (18) converts the frequency-modulated luminance signal YFM and the low-frequency converted carrier color signal crt (n-air head (31), as will be described later).
In the magneto-electric transducer system that performs multiplex recording on the tracks on the magnetic tape (32), the frequency shown by the broken line is the second-order beat component of 2 fc, which is theoretically generated due to the third-order distortion. On the other hand, the above low-pass converted carrier color signal CF
From L, as shown by the solid line in FIG. 2, a frequency 2. f
A beat cancel signal SIC of c is formed. The beat cancellation signal forming circuit (1st) includes, for example, a doubler circuit (18A) using a balanced modulator and a tuned amplifier circuit (18B) with a passing center frequency of 2.fc as shown in FIG. 3A. or an inverter (18C) and a correlator (180) as shown in Figure 3.
A configuration configured with , etc. is used.

In this embodiment, the beat cancel signal forming circuit (18) includes the level adjusting variable resistor (16).
Since the beat cancellation signal 5IIC is formed from the carrier color signal crt supplied via the variable resistor (
16), the carrier color signal crt
along with the signal level of the beat cancellation signal Sac
The signal level is also adjusted at the same time, so that the amount of cancellation is always optimized.

Further, the signal addition circuit (23) performs a signal addition process of adding the beat cancellation signal 5IIC to the luminance signal Y supplied from the Y/C separation circuit (11) via the clamp circuit (22). The addition output signal from the signal addition circuit (23) is sent to a clip circuit (24) that performs clip processing such as dark clip processing and white clip processing.
) is supplied to a frequency modulation circuit (26) via a pre-emphasis circuit (24) connected thereto.

Then, the frequency-modulated luminance signal YFM taken out from the frequency modulation circuit (26) via the bypass filter (27) is supplied to the recording amplifier circuit (29) via the level adjustment variable resistor (28). is amplified by this recording amplification circuit (29) and sent to the signal synthesis circuit (30).
is given to. The signal synthesis circuit (30) combines the luminance signals Y, H and the low frequency converted carrier color signal CF.
A recording signal SREC is formed by adding and combining the signals L and L, and this recording signal sIIEc is applied to the recording hand (31).
The above luminance signal YFM is placed on the trunk on the magnetic tape (32).
A multiplexing process is performed to multiplex record the carrier wave color signal CFL and the low frequency converted carrier color signal CFL.

That is, in the magnetic recording apparatus of this embodiment, a beat cancellation signal 5IIc having a frequency 2·fc, which is twice the color subcarrier frequency fc, is generated from the carrier wave color signal CFL that has been low-pass converted.
is formed by the beat cancel signal forming circuit (17),
A signal addition circuit (23) adds the beat cancellation signal SIC to the luminance signal Y, frequency-modulates the luminance signal Y to which the beat cancellation signal SRc has been added, and converts this frequency-modulated luminance signal YFM and the above-mentioned low frequency conversion. The signal synthesis circuit (30) adds and synthesizes the carrier wave color signals CFL and the magnetic head (31) to which the recording signal S Rtc is given as a composite output from the signal synthesis circuit (30). The frequency-modulated luminance signal Y8 and the low-frequency-converted carrier wave color are obtained while canceling the second-order beat component caused by the third-order distortion of the magneto-electric conversion system recorded on the track on the magnetic tape (32). The signal CFL is multiplex recorded on the same trunk on the magnetic tape (32).

Further, the magnetic recording apparatus of this embodiment has second and third signal input terminals ( 41).

(42), the carrier color signal CFLI11 in the low frequency converted state and the luminance signal YFMIN are sent from the second and third signal input terminals (41) and (42) to each of the signal changeover switches (15). , (21) to each signal processing system.

11. Effects of the Invention In the magnetic recording device according to the present invention, in the recording system, a beat cancellation signal having a frequency twice the color subcarrier frequency is formed from the low frequency converted carrier color signal in a beat cancellation signal forming circuit, A signal addition circuit adds the beat cancellation signal to the luminance signal, frequency-modulates the luminance signal to which the beat cancellation signal is added, and adds and synthesizes it with the low-frequency converted carrier color signal, thereby generating a magnetoelectric conversion system. Since the secondary beat components of the luminance signal and chrominance signal caused by third-order distortion are canceled in advance in the recording system and multiplexed recording is performed on the same track, there is a risk that the original luminance signal may deteriorate in principle. The secondary beat component can be effectively canceled without any distortion and with a simple circuit configuration. In addition, in the magnetic recording device according to the present invention, since recording is performed in a state where the secondary beat component caused by the third-order distortion of the magnetoelectric conversion system is canceled, even when performing compatible playback, the secondary beat component There is no need to provide a signal processing means for canceling the components in the reproduction system.

Therefore, by applying the present invention, the secondary beat component of the luminance signal and the chrominance signal, which is caused by the third-order distortion of the magneto-electric conversion system in a multi-recording VTR, can be efficiently canceled with a simple circuit configuration. This makes it possible to perform high-quality recording and playback.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic recording device according to the present invention, and FIG. 2 is for explaining the principle of the operation of canceling the second-order beat component caused by the third-order distortion of the magnetoelectric conversion system in the above-mentioned magnetic recording device. Schematic diagram of Figure 3 A and Figure 3 [D
B is a block diagram showing an example of each configuration of a beat cancel signal forming circuit used in the magnetic recording device. Figure 4A, Figure 4B and Figure 4C are Vs of the multiple recording system.
FIG. 4A is a schematic diagram for explaining the principle of generation of second-order beat components of luminance signals and color signals caused by third-order distortion of a magnetoelectric conversion system in a TR, and FIG. 4A shows a frequency spectrum of a recording signal. , FIG. 4B shows the frequency spectrum of the reproduced signal, and FIG. 4C shows the frequency spectrum of the secondary beat component included in the reproduced signal. FIGS. 5 and 6 are block diagrams showing examples of the configuration of a reproduction system of a conventional multiple recording VTR having a function of canceling the secondary beat component. (10)...Signal input terminal (11)...Y/C separation circuit (12)...
Frequency conversion circuit (17) Beat cancellation signal forming circuit (23) Signal addition circuit (26) Frequency modulation circuit (30 )...
...Signal synthesis circuit (31) ...Magnetic head (32) ...Magnetic tape

Claims (1)

[Claims] In a magnetic recording device that adds and combines a low-band-converted carrier color signal and a frequency-modulated luminance signal and records them on the same track, the color subcarrier frequency is calculated from the low-band converted carrier color signal. 2
A beat cancellation signal forming circuit that forms a beat cancellation signal with double the frequency and a signal addition circuit that adds the beat cancellation signal to the luminance signal are provided, and the luminance signal to which the beat cancellation signal is added is frequency modulated, A magnetic recording device characterized by performing additive synthesis with a low frequency converted carrier wave color signal and multiplexing the signal on the same track.