JPH0683482B2 - Video signal recorder - Google Patents

Description

The present invention relates to a video recording device, and more particularly to audio and video information.
VT for FM frequency multiplexing and recording with a rotating head
It is suitable for R.

[Conventional technology]

In a home VTR, a luminance signal is FM-modulated, a chroma signal is converted to a low frequency band and recorded / reproduced with a rotary head, and a voice signal is recorded / reproduced with a fixed head in a longitudinal direction of a magnetic tape. Things are common. However, when the recording density is increased and the recording time is lengthened, the quality of the reproduced audio signal is significantly deteriorated due to the decrease in tape speed.

For this reason, in addition to the conventional FM luminance Y + low frequency chroma C multiplexing method as shown in the frequency spectrum diagram of FIG. 1, FM audio is added to the valley between the luminance FM and low frequency chroma as shown in FIG. signal
A method is adopted in which AFM is inserted to obtain high-quality reproduced sound. In the system of FIG. 2, the band of the FM luminance signal YFM is shifted to the high frequency side by about 400 kHz, for example. A trap circuit is inserted in each band where FM brightness and low frequency chroma FM sound overlap, so that the brightness and chroma are not disturbed by the beat with the FM sound signal.

Also in the conventional VTR in which the lower sideband of the FM luminance (YFM) and the low frequency chroma C partially overlap as shown in FIG. 1, a high pass filter is inserted after FM modulation in the luminance recording system to The sidebands are suppressed so that they do not interfere with each other.

[Problems to be solved by the invention]

However, the lower band of the luminance signal may be significantly reduced by the trap circuit, and the horizontal resolution of the reproduced image may deteriorate to about 210 lines. Further, the above high-pass circuit has also been an obstacle to improving the resolution.

On the other hand, due to improvements in magnetic tape and circuit technology, high frequency recording / reproducing performance is improving year by year. However, even if the high-frequency limit of recording / playback performance is extended, there is a limitation in compatibility with conventional devices, and it has not been possible to achieve significant image quality improvement.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a reproduced video with little deterioration in resolution while maintaining consistency with a conventional device.

[Means for solving problems]

The video recording apparatus of the present invention separates an input video signal into a luminance signal and a color signal, FM-modulates the luminance signal, frequency-converts the color signal into a low frequency band, and rotates the rotary head together with the FM-modulated luminance signal. In a video signal recording device adapted to record on a magnetic tape by using the FM audio signal superimposing means (adder) for inserting the FM audio signal in the band between the FM modulated luminance signal and the low frequency conversion color signal. 4), carrier frequency selecting means (changeover switch 8) for selectively switching the carrier frequency of the FM modulated luminance signal to the first and second values, and the carrier frequency of the FM modulated luminance signal by the carrier frequency selecting means. Depending on the selection, the recording current values of the FM modulated luminance signal, the low frequency conversion color signal and the FM audio signal are switched, and the FM modulated luminance signal is recorded as the bias signal by the same head. The low frequency converted color signal and FM
Recording current switching means (switching switch 9) for correcting the reproduction level of the audio signal by switching the recording current value corresponding to the change in bias effect due to different carrier frequencies is provided.

[Action]

By switching the carrier frequency of the FM modulated luminance signal according to the magnetic tape of different characteristics, it is possible to increase the recording bandwidth of the luminance signal and increase the resolution of the reproduced image when using a magnetic tape with good high frequency performance. . In this case, the recording current values of the FM luminance signal, the low-frequency conversion color signal, and the FM audio signal are switched according to the selection of the carrier frequency, which allows the low-frequency conversion color signal to correspond to the change in the bias effect due to different carrier frequencies. And the playback level of the FM audio signal is corrected. Therefore, not only the FM luminance signal but also the low-frequency converted color signal and the FM audio signal, the recording / reproducing characteristics are optimized according to the type of tape, the resolution is further improved, and a high quality reproduced audio is obtained.

When using a normal magnetic tape, the FM carrier frequency is switched to the lower side to maintain the compatibility of recording and reproducing with conventional devices.

〔Example〕

 The configuration of the present invention will be described below based on examples.

FIG. 3 is a block diagram of a main part of a VTR recording system to which the present invention is applied. In FIG. 3, an input video signal is converted into an FM signal by an FM modulator 3 through an adder 1 and a pre-emphasis circuit 2, and further passes through an adder 4, a recording amplifier 5, a rotary magnetic head 6 and a magnetic tape 7. Recorded in. The low-pass converted chroma signal C and FM audio signal AFM are added to the adder 4.

A DC bias is superimposed on the input adder 1 via a manual changeover switch 8. The changeover switch 8 shifts the center carrier frequency f ₀ of the FM luminance signal. At the time of normal recording / reproducing, the changeover switch 8 is connected to the N contact, and the FM luminance signal YFM having the carrier frequency f ₀ as shown in FIG. 1 is recorded. Next, change the switch 8 to the high-fidelity mode contact F1.
, The DC bias E1 is added to the input video signal, and the carrier frequency of the FM luminance signal YFM is shifted to the high frequency side by about 400 kHz as shown in FIG. In this state, FM
The FM audio signal is multiplexed in the valley between the luminance and the low frequency chroma.

Further, when the selector switch 8 is switched to the high fidelity high image quality mode contact F2, the DC bias E2 is added to the input video signal, and the carrier frequency f ₀ of the FM luminance signal YFM is further shifted to the high frequency side by Δf as shown in FIG. It Δf can be set to, for example, 400 kHz (shifted by 800 kHz from the normal recording / reproducing) corresponding to the high frequency recording / reproducing limit of YFM.

By this operation, the lower limit of the FM luminance signal band is less likely to overlap with the voice FM band as shown in FIG. 4, and therefore, the lower side band of the FM luminance signal is lessened by the trap circuit during recording / reproducing, It is possible to obtain a high quality reproduced image with little deterioration and high resolution. Also, the interference from the FM luminance signal to the FM audio signal is reduced, and the reproduced sound quality is improved.

If FM audio is not multiplexed, the high-pass circuit for reducing the crossover obstacle between the luminance and the low frequency chroma in the high image quality mode can be disabled. As a result, the lower band of the FM luminance signal is less likely to be scraped, so that the recording bandwidth of the luminance signal is expanded and the resolution of the reproduced image is improved.

In this case, the high frequency performance of the magnetic tape is sufficiently adaptable to the increase in the high frequency recording signal level due to the shift of the carrier frequency. It is also assumed that the VTR recording / playback performance is sufficiently high-frequency compensated.

As shown in FIG. 5, when the carrier frequency of the FM luminance signal is increased by Δf, the optimum recording current Iopt
Decreases. Therefore, as shown in FIG.
It is preferable that a variable bias is supplied to the gain control input of (1) through a changeover switch 9 which is interlocked with the changeover switch 8 so that an optimum recording current according to the mode change is generated. In the hi-fi mode, the voltage E3 is applied to the gain control input of the recording amplifier 5 through the contact F1 of the changeover switch 9, and the recording current is led to the head 6 with a required gain. Further, in the high image quality hi-fi mode, the voltage E4 is applied to the gain control input of the recording amplifier 5 through the contact F2 of the changeover switch 9, and the gain of the recording current is somewhat reduced.

Further, since the reproduction level of the FM audio signal and the low frequency conversion chroma signal is increased by the bias effect due to the shift up of the carrier frequency of the FM luminance signal, the recording current of these components may be reduced accordingly.

It is premised that the VTR of this embodiment has a higher high frequency recording / reproducing characteristic than that of a normal one, and thus a sufficient reproduction output can be obtained at the upper end of the FM luminance signal band. When it is possible to improve the high frequency characteristics, it is preferable that the changeover switches 8 and 9 shown in FIG. 3 are interlocked with the magnetic tape type selector switch.

Without being limited to the above embodiment, for example, in FIG.
The free-running frequency of the FM modulator 3 may be switched to shift the carrier frequency of the FM luminance signal.

〔The invention's effect〕

According to the present invention, it is possible to cope with magnetic tapes having different characteristics.
When the carrier frequency of the FM modulated luminance signal is switched and the recording bandwidth of the luminance signal is widened to increase the resolution of the reproduced image when using a magnetic tape with good high frequency performance, the carrier frequency is selected according to the selection. The recording current values of the FM luminance signal, low-frequency conversion color signal, and FM audio signal are switched, which corrects the reproduction levels of the low-frequency conversion color signal and FM audio signal in response to changes in the bias effect due to different carrier frequencies. Therefore, not only the FM luminance signal but also the low-frequency conversion color signal and FM audio signal are optimized for recording / reproducing characteristics according to the type of tape, and the resolution is further improved and high quality reproduced audio is obtained. .

[Brief description of drawings]

FIG. 1 is a frequency spectrum diagram showing the recording band distribution of FM luminance signals and low-frequency conversion color signals in a conventional home VTR, FIG. 2 is a frequency spectrum diagram when FM audio signals are multiplexed, and FIG. A block diagram of a main part of a recording system of a VTR to which the invention is applied, FIG. 4 is a frequency spectrum diagram showing a band distribution of a luminance signal, a color signal and a voice signal of the embodiment of FIG. 3, and FIG. 6 is a graph showing frequency vs. optimum recording current amount. In the reference numerals used in the drawings, 1 ... Adder 3 ... FM modulator 5 ... Recording amplifier 6 ... Rotating magnetic head 7 ... Magnetic tape 8, 9 ... Changeover switch.

Claims (2)

[Claims] 1. An input video signal is separated into a luminance signal and a chrominance signal, the luminance signal is FM-modulated, and the chrominance signal is frequency-converted to a low frequency band, and the FM signal and the luminance signal are magnetically modulated using a rotary head. In a video signal recording device adapted to record on a tape, an FM audio signal superimposing means for inserting an FM audio signal in a band between the FM modulation brightness signal and the low frequency conversion color signal, and the FM modulation brightness signal. Carrier frequency selecting means for selectively switching the carrier frequency of the FM modulating luminance signal to the first and second values and the carrier frequency selecting means for selecting the carrier frequency of the FM modulated luminance signal. The low-frequency conversion color signal and FM recorded by the same head by switching the recording current value of the frequency conversion color signal and the FM audio signal and using the FM modulation luminance signal as a bias signal
A video signal recording device, comprising: a recording current switching unit that corrects a reproduction level of an audio signal by switching a recording current value corresponding to a change in bias effect due to different carrier frequencies. 2. The video signal according to claim 1, wherein the carrier frequency selecting means is adapted to operate in accordance with types of tape having different recording high frequency limits. Recording device.