JPS58103279A - Video and sound signal recorder - Google Patents

Abstract

PURPOSE:To record the video signal with high density and at the same time to prevent the quality deterioration of the sound signal, by giving a control so that the recording level of the FM-modulated sound signal is varied contrary to the level change of the original sound signal. CONSTITUTION:For the left and right signals SL ans SR of the stereo sound signals supplied through sound input terminals 1 and 2, the modulated output occupying the frequency band different from the video frequency band is set by the frequency modulators 6 and 7 respectively. While a level detector 21 detects the level of the sound signal and produces an output in response to the detected level. Based on this output, the level control parts 17 and 19 change the levels of the modulated outputs given from the modulators 6 and 7 in a contrary way to the level change of the sound signal. This modulated output is mixed 24 with the outputs of the parts 17 and 19. This output signal of mixture is recorded on a recording medium by the recording head parts 30 and 32.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video and audio signal recording device 1a for recording a video signal and audio fgM comprising a ten vision signal f:ht by forming a recording track on a recording medium. 1! a
In addition to being able to record video signals at high density, it also allows audio signals to be recorded without any loss of quality, with minimal interference with video signals during playback, and with an excellent signal-to-noise ratio. The present invention aims to propose a video and audio signal recording device capable of recording so as to obtain a reproduced audio signal output having a sufficient dynamic range. 1 When a color television signal is recorded on a magnetic tape, the carrier color signal and luminance signal that form the color video signal are separated, the carrier color signal is frequency-converted to the low frequency band side, and the luminance signal is frequency-converted to the high frequency band side. After frequency modulation (hereinafter referred to as FM modulation) on the frequency band side, both are mixed and recorded on recording tracks arranged at an angle with respect to the running direction of the magnetic tape (hereinafter referred to as inclined tracks). ,
In addition, the mainstream format is one in which the audio signal is recorded in a recording track (hereinafter referred to as sound Ii track) extending in the direction along the running direction of the magnetic tape1.In such a self-recording format, Color screening 1. 'τ', that is, the inclined track on which the low frequency converted carrier color signal and the FM modulated luminance signal on the high frequency side are recorded, are magnetically operated alternately by two rotating magnetic heads to which these two signals are supplied. The tape is formed by scanning the tape at an angle with respect to its traveling direction, and at this time, in order to increase the recording density and enable long-term recording, gaps, so-called gaps, are created between adjacent inclined tracks. , it has been proposed to have the sloped tracks adjacent to each other without placing guard bands.

In this case, crosstalk between adjacent inclined tracks becomes a problem during playback, but by making the azimuth angles of the two rotating magnetic heads different from each other, the brightness of the FM modulated on the high frequency side during playback can be reduced. The azimuth loss for crosstalk components from adjacent tracks is increased, and the phase of the low-pass converted carrier chrominance signal whose azimuth loss effect is small is
Every t inclined track is continuous, and every other inclined track is t'T.
By inverting and recording every horizontal period, and passing a predetermined phase restoration on the reproduced carrier color signal and passing it through a comb-shaped characteristic filter, it is possible to remove a stalk component from an adjacent track. , solving the crosstalk problem. Further, the audio track is continuously formed, for example, on the upper end side of the magnetic tape by a fixed head that receives audio signals being constantly in contact with the running magnetic tape. At this time, the audio signal is, for example,
When there are two stereo channels, such as a left and right stereo signal, the left and right signals are fed to separate fixed heads, and these two fixed heads form two parallel audio tracks. 1. By the way, when high-density recording of color video signals as described above is attempted, the relative speed between the magnetic tape and the rotating magnetic head is maintained at a predetermined level, and the running of the magnetic tape is The speed is extremely low, for example, about 3 cm/sec, so the relative speed between the fixed head that forms the entire audio track and the magnetic tape is extremely low, and the recorded audio signal is This has the disadvantage that the quality of the product deteriorates.

Therefore, for example, the audio signal is mixed with the color video signal as an FM modulated signal and supplied to the rotating magnetic head, and is recorded together with the color video signal on the inclined track where the color video signal is originally recorded. In response to the low relative speed between the recording head and the magnetic tape of the recorded audio signal, methods have been proposed to prevent the quality from deteriorating. In this case, the frequency band occupied by the FM-modulated audio signal is said to be different from the frequency band of the color video signal, but in order to limit the frequency band of the entire recording signal, it is compared to the frequency band of the color video signal. 1. Therefore, in order to improve the signal-to-noise ratio (hereinafter referred to as S/N ratio) of the reproduced audio signal output and widen the dynamic range, recording of FM-modulated audio signals is required. If the level is increased, the interference with the color video signal during playback will become significant, and the playback color video signal will easily cause beat disturbances on the screen, degrading the image quality. If the recording level of the FM-modulated sound PLj signal is reduced in order to reduce interference with the video signal, the S/N ratio of the reproduced audio signal output will decrease, resulting in a reduction in the dynamic range and making it difficult to obtain high-quality reproduced audio. The disadvantage was that it was no longer possible to obtain

The present invention has been made in view of the above, and when recording video signals and audio signals on a magnetic tape, the audio signals are converted into FM modulated signals occupying a frequency band different from the frequency band of the video signals. is supplied to the rotating magnetic head together with the video signal for recording, and at this time, the F
By controlling the recording level of the M-modulated audio signal so that it changes inversely to the level change of the original audio signal, it is possible to record the video signal at high density, and at the same time, it is possible to reduce the quality of the audio signal. To provide a video and audio signal recording device capable of recording in such a way that a reproduced audio signal output with an excellent S/N ratio and a sufficient dynamic range can be obtained without interference to video signals during playback. It provides: Hereinafter, embodiments of the present invention will be explained with reference to the drawings. .

FIG. 1 shows essential parts of an example of a video and audio signal recording device according to the present invention. This example shows the audio to be recorded (fi
Two channel audio signals, a stereo left signal and a right signal, are supplied as signals, and these two channel audio signals are used as FM-modulated audio signals of the first to ρth riffs.
In this example, the left signal SL and right signal SR of the stereo V audio signal are supplied to the audio input terminals 1 and 2, respectively, which are to be recorded together with the color video signal. This left signal SL sequentially passes through an automatic gain control amplifier circuit 3, a noise reduction circuit, and a pre-emphasis circuit 5.
1 supplied to each of the second FM modulators 6 and 7
, In addition, the right signal SR is similarly connected to the automatic gain control amplifier circuit g, the noise reduction ρ1 path 9, and the Buri/Fasis circuit 10.
f sequentially, the third and first FM modulators 〆l and 1
2.

The first and second FM modulators 6 and 7 have frequencies f/ and f, a higher frequency f2, for example f.

= t, f 2 = / , 'I 7 in 325M11z
5MH2 carrier waves are each FM-modulated with the left signal SL with the same frequency shift width, about 100 to tsokH2, and the FM-modulated left signals with different frequency shift bands are sent to each output end. LFt and RF2 (hereinafter referred to as left FM signals) are obtained. Further, the third and second FM modulators// and the final FM modulators have a frequency f higher than f2.
3 and higher frequency f than f3, ρ1j, for example, f
3 = / , &2!; f in MHz (< ==
/, 77 MHz, respectively, are FM-modulated with the right signal SR with the same frequency shift width as above, and the FM-modulated right signal (with different frequency shift bands) is output to each output end.
Hereinafter, RF3 and RFK are obtained (hereinafter referred to as the right FM signal).1 Here, the frequency '/+f2+fJ and f are the beat noise between the two adjacent FM signals after demodulation of the left FM signal and the right FM signal. The components are selected to be outside the reproduced audio signal band, and in the above example, this interval is 15θkHz. Signal R
F3 and RF are each connected to a corresponding bandpass filter/
Pass through J, /e, /S and 16. These left FM signals LFl and RF2 and right FM signals RF3 and RF
u, their levels are LFt < RF2 < RF
The frequency spectrum is as shown in Figure 2 (horizontal axis: frequency - f), and the frequency shifts are adjusted so that J < RF. However, the frequency shift bands adjacent to q and ii are very close to each other, and the overall frequency band is relatively narrow. Bandpass filter /31/'I/
left FM signals LF/and RF2 from S and 16, and
The right FM signals RF3 and RF are supplied to variable gain amplifier circuits /7, 7g, /9 and 20, respectively.

Further, the left signal SL and the right signal SR from the noise reduction circuits ψ and 9 are supplied to the V level detection circuits 21 and 22, respectively. It forms a peak level detection circuit for the right signal SR, and generates outputs corresponding to the peak levels of the left signal S, L and right signal SR at their respective output terminals. The output circuit 21 generates an output that changes according to the level change of the left signal SL supplied from the audio input terminal l, and the level detection circuit 22 generates an output that changes according to the level change of the right signal SR supplied from the audio input terminal k. The output money is the main thing. Then, the output of the level detection circuit 21 is supplied to the variable gain amplifier circuits 17 and 7g, and the variable gain amplifier circuit l? and the gain/G of 7g is the level detection circuit 2.
As the output of the level detection circuit 21 becomes larger, the output becomes smaller, and as the output of the level detection circuit 21 becomes smaller, the output becomes larger. . j As a result, the variable gain amplifier circuit l? The levels of the amplified left FM signals LF/ and RF2 obtained at the output terminals of the left signal SL and ig are small when the level of the left signal SL is high, and are large when the 7 bells of the left signal SL are small, It is assumed that the change in level is opposite to that of the left signal SL. Similarly, the output of the level detection circuit 22 is output from the variable gain amplifier circuits 19 and 20.
The gain G of the variable gain amplifier circuits 19 and 20 is supplied to
is controlled to change inversely to the change in the output of the level detection circuit 22 in the same manner as in the case of the variable gain amplifier circuits 17 and 7g. As a result, the output terminals of the variable gain amplifier circuits 19 and 2θ The levels of the resulting amplified right FM signals RF3 and RF& are small when the level of the right signal SR is large, and large when the level of the right signal SR is small, and are opposite to the level change of the right signal SR. It is assumed that changes will occur.

Next, the left FM whose level is controlled by the variable gain amplifier circuit 17 is
The signal LF/ and the right FM signal RF3 whose level has been controlled by the variable gain amplifier circuit 19 are mixed by the mixing circuit 23, and the left FM signal LF2 whose level has been controlled by the variable gain amplifier circuit/g is mixed with the level by the variable gain amplifier circuit 20. Controlled right FM signal R
Further, the mixed output of the left FM signal LF/ from the mixing circuit 23 and the right FM signal RF3, and the left FM signal LF2 and the right F from the mixing circuit 2 are mixed.
The carrier color signal C from the terminal 27, which is a video signal, and the FM-modulated luminance signal Lm from the terminal 2g are mixed into the mixed output with the M signal RFK in the mixing circuit 25 and the roller. Here, the carrier color signal C is a carrier color signal separated from a color video signal, and the frequency of its color subcarrier is the above-mentioned frequency f, a lower frequency fC, 1ull, fc=
In addition, the FM-modulated luminance signal Lm has the synchronization signal of the luminance signal separated from the color video signal, and the leading edge of the synchronization signal is at the above-mentioned frequency f, which is higher than the frequency f. higher frequency fs, for example, f,=
l'MH2, and its white peak (maximum amplitude part) is at a predetermined frequency from fs, for example, 1.2MHz,
the higher frequency fp, e.g. t p = s, 2
The level of the carrier color signal C is higher than the level of any of the left FM signals LF/ and LF2, and the right FM signals RF3 and RF. FM-modulated luminance signal Lm
The level of the carrier color signal C is higher than that of the carrier color signal C1. An example of the relationship between the frequency spectrum and each level between RF3 and RF is shown in Figure 3 (horizontal axis is frequency/f and vertical axis is level/l)1.As is clear from this, In a narrow frequency band between the upper limit of the band of the carrier color signal C located on the lower band side and the lower limit of the band of the FM-modulated luminance signal Lm extending to the lower band side, the left FM signals LFl and 1 are ．． ? , and right FM signals RF3 and RF are sequentially located close to each other, so that they do not overwhelm the band of the carrier color signal C and the FM-modulated luminance signal Lm as much as possible. In addition,
1m indicates a luminance signal separated from a color video signal,
.

Then, from the mixing circuit 25, the carrier color signal C1FM modulated luminance signal [1ms left FM signal LF/and right FM
The first mixed output Mi mixed with the signal RF3 is supplied to the rotary magnetic head 30 via the recording amplifier circuit 29, and the carrier color signal C from the mixing circuit 26, the FM-modulated luminance signal Lm, and the left FM signal 1. F2 and right FM signal RF
, the second mixed output M2 is sent to the recording amplifier circuit 3'.
The magnetic heads 30 and 32 have different azimuth angles and alternately form oblique tracks with no guards on the magnetic tape. , first mixed output Mt
and a second mixed output M2, where the first mixed output Mt has a frequency spectrum as shown in Figure V and the second mixed output M2 has a frequency spectrum as shown in Figure S. As shown in FIG. 6, these frequency spectra are determined by the adjacent slopes formed on the magnetic tape T by the magnetic heads 30 and 32 having different azimuth angles. Track 1.
and t2, respectively. , Therefore, regarding audio signals, the ones recorded on the same inclined track are the left FM signal LF/ and the right FM signal RF3, and the left FM signal LF2 and the right F'M signal RFF, which are not adjacent to each other.
The carrier frequencies of the audio signals in adjacent inclined trunks will not match.1 In FIG. 3. Note that the conveyance color signals C and FM are recorded individually for the inclined trunk 1° and t2.
The modulated luminance signal Lm is assumed to correspond to l vertical periods, l fields, and l fields. .

In addition, in this example, the left signal SL and the right signal S RK
Audio signal recording system 33 and 3 by identification head
q is also provided, and the left signal SL and right signal SR from the audio input terminals 1 and 2 are supplied to the audio signal distribution systems 33 and 3 by fixed heads, respectively, as shown in FIG. As described above, the device according to the present invention records 1° on the two audio tracks tL' and tR' formed on the upper end side of the magnetic tape T. luminance signals I, m and F
M-modulated audio signals are recorded by forming inclined tracks using a common 1111 rotating magnetic head, but the relative speed between the rotating magnetic head and the magnetic tape is sufficient to record video signals. Because it is said to be high-speed, there is no risk of deterioration in the quality of the recorded audio signal, and it is also possible to record multiple channels of audio signals, such as the two channels of the right signal, using a narrow frequency band. Note 'LL
This avoids the compression of the frequency of the imaging signal, and in the device according to the present invention, the FM modulated audio signals (LF/, LF2, RF3 and RFv) 7 bells are level control section (variable gain amplifier circuit/7~20
), the level of the original audio signal (SL and SR) to be recorded from the audio input terminal is set to be low when it is a dog, and the VpejL of the original audio signal.

This means that if the original audio signal level is high and the S/N ratio is good, the recording level of the FM modulated 1° 1 voice signal recorded together with the video signal will be high. ° is set to be small to minimize interference with video signals during playback. At this time, since the original level of the original audio signal is dog and the S/N ratio is good, the S/N of the reproduced audio signal output obtained from the recorded FM modulated audio signal is
The ratio does not suffer much and a sufficient dynamic range can be obtained. Tit, <'p Although the recording level of the M-modulated audio signal is high and there is some interference with the video signal during playback, the S/N ratio is improved and the dynamic range is expanded. 1. As a result, it is possible to obtain a reproduced audio signal output that has an excellent S/N ratio and a sufficient dynamic range on average, and , especially when the level of the original audio signal to be recorded is low, it is possible to reduce the interference of the FM-modulated audio 1st signal with the video signal during playback.Furthermore,
As a result of the interference of the FM-modulated audio signal with the video signal, the reproduced video is reproduced. Even if beat noise occurs on the image, this beat noise is Figure q shows a first level detection circuit that generates an output that changes in accordance with level changes of the left signal SL and right signal SR.
In this example, level detection (lower) paths ν' and 22' are used for the FM modulation 'ryL, Fl and the right FM signal RFJ, respectively. Cut out the frequency discrimination circuit mold. Then, the first and 30':F are connected to the respective input terminals.
Left F'M signal LF/and right FM signal RF from M modulator
3 is supplied to each output terminal, and an output corresponding to the frequency deviation of the left FM signal LF/and right FM signal RF3, that is, an output corresponding to the level of the left signal SL and right signal SR is obtained. . , these level detection circuits 2/' and 22'
The gain/G of the variable gain amplifier circuits 17 to 20 is controlled by the output of the circuit, and the frequency discrimination circuit for the first signal RFV may be of the form 1tlj.

Furthermore, in the above-mentioned Embodiment 11, the two channels of audio (t-j), the left signal S7 and the right signal SR, are respectively FM
The q FM modulations obtained by modulation are sequentially adjacent to each other with different frequency ranges, and are obtained by modulating the audio signal LF.
/ , LF2. RF3 and RFv, which are recorded together with video signals on a plurality of inclined tracks formed alternately with guard bands by two rotating magnetic heads having different azimuth angles. The frequency shift bands of the FM-modulated audio signals recorded on the same track are not adjacent to each other, and the carrier frequencies of the FM-modulated audio signals recorded on two adjacent inclined tracks are Although they are set not to match, this allows the use of a relatively narrow frequency band that does not overwhelm the video signal band when recording the two-channel audio signal as an eFM modulated signal. Moreover, during playback, the two are sufficiently separated from each other.
The reproduction signal of the channel can be obtained with interference caused by crosstalk components from adjacent tracks extremely reduced.

Furthermore, since the above-described embodiment also records audio signals using a fixed head similar to the conventional one, video and audio signals can be reproduced from the magnetic tape recorded using this example by a conventional device having a fixed head for audio reproduction. It is possible to obtain playback video and audio signals, and is also compatible with conventional devices.

Note that, unlike the above example, the device according to the present invention can be configured as a video and audio signal recording device that records an l-channel audio signal as seven FM-modulated audio signals together with a video signal. Of course, it is possible, and various other embodiments may be taken without departing from the gist of the invention. .

[Brief explanation of the drawing]

FIG. 1 is a block connection diagram showing essential parts of an example of a video and audio signal recording device according to the present invention, and FIG. FIGS. 3, V, and 5 are frequency spectrum diagrams used to explain the operation of the reli shown in FIG. 1, and FIG. FIG. 7 is a block connection diagram showing a part of another ρ1j of the video and audio signal recording device according to the present invention. 1 and 2 are audio input terminals, 1 and 10 are 1/
:I, /, 'l, /'; and /A are bandpass filters,
/'? , /g, /9 and 20 are variable gain amplifier circuits,
, 2/', 22 and 22' are level detection M circuits,
ko J, 2 (4, ko S and 26 are mixed circuits, ko 9 and 31
is a circuit for recording increase +p', 3θ and 32 are [rotating magnetic head 1]

Claims (1)

[Claims] A carrier wave of a predetermined frequency is frequency modulated with an audio signal, and video 4
a frequency modulation section that obtains a modulated output f occupying a frequency band different from the frequency band of No. 1'j; a level detection section that detects the level of the audio signal and generates an output according to the level; The output also includes a V-pel control section that controls the level of the modulated output from the frequency modulation section so that the level change is opposite to the level change of the audio signal, and the level control section controls the level. a mixing section that mixes the modulated output and the video signal; 1. A video and audio signal recording device 1, comprising a recording head unit that records the output from the mixing unit on a recording medium.