JPS6022709A - Rotary head type recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the recording/reproducing of stereo signals and at the same time to maintain the interchangeability with a conventional device for the titled device, by winding a tape around a rotary drum with an extra length as an overlap area at an angle larger than 180 deg. by alpha deg. and recording with time compression the Lch component of the stereo signal. CONSTITUTION:A tape is wound around a rotary drum 2 at its entrance part with an extra length as an overlap area by alpha deg. compared with a conventional VTR. Thus a recording pattern 6 corresponding to alpha deg. is formed at the entrance part of a conventional recording pattern 5. The Lch of a terminal 14 is supplied to a time axis control circuit 46. The frequency of a multiplier 50 is multiplied in response to 180 deg. and alpha deg. and therefore the Lch receives time compression and undergoes FM modulation through an FM modulation circuit 32. This FM modulated Lch is recorded to the region 6 corresponding to alpha deg. by a video head 44. A mixture signal of the sound sum signal and the video signal is recorded to the region 5 of the tape from a mixer 26 by a head 44. In a reproduction mode both the mixture signal and the Lch are reproduced by a head 42. While the mixture signal and the Lch recorded in the next period are reproduced by the head 44.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to a rotary head type recording and recording/reproducing device,
In particular, the present invention relates to an apparatus for forming a trunk having a first area and a second area on a recording medium using a rotary head in 11 ρ orders, and recording signals included in each area.

<Description of the Prior Art> The following is a rotating two-head helical scan type video tape in which a magnetic tape is wound around a rotating cylinder having two rotating heads to sequentially form diagonal tracks and record video signals and audio signals on the tracks. An example in which the present invention is applied to a recorder C (VTR) will be explained.

Conventionally, when video signals and audio signals are recorded and played back by a VTR, the video signal is recorded by a rotating head scanning a video track diagonal to the tape, so that the video signal is transferred between the head and the tape. On the other hand, audio signals are recorded by forming audio tracks in the longitudinal direction of the tape using a fixed head.

However, in recent years, home VTRs and the like have been required to have longer running times and higher density, and as a result, tape running speeds are becoming slower. Therefore, it is difficult for audio signals recorded and reproduced with a fixed head to have sufficient characteristics in terms of frequency characteristics, wow/flutter, signal-to-noise ratio, etc., resulting in the disadvantage that high-quality reproduced audio cannot be obtained.

Therefore, an apparatus has been proposed in which an audio signal is FM-modulated, multiplexed with a composite video signal, and recorded and reproduced on diagonal tracks using a rotary head.

FIG. 1 is a diagram showing the bands of each signal of the conventional VTR as described above, in which Y is a luminance signal, C is a chroma signal,
A indicates an audio signal. As shown, F M
The audio signal is FM-modulated and multiplexed in a frequency band between the modulated luminance signal and the low-frequency converted chroma signal. However, in such a device, in order to record and reproduce the luminance signal with good resolution, it is necessary to secure as much bandwidth as possible for the FM-modified luminance signal.

Therefore, the band that can be secured for recording and reproducing audio signals becomes narrower, and only one channel is required to ensure a certain level (sound quality) of the frequency characteristics and dynamic range of the recorded and reproduced audio signals. Note 0: You will no longer be able to play.

Further, if discontinuity occurs in the reproduced FM modulated audio signal due to dropout or head switching, large amplitude noise will occur in the reproduced audio signal after demodulation. This noise further causes transients, making the reproduced sound harsh. In the case of a signal with temporal correlation such as a video signal, it is possible to compensate for such noise by replacing other parts before and after it, but in the case of a signal with no temporal correlation such as an audio signal. In this case, it cannot be replaced with other parts.

<Object of the Invention> The present invention makes it possible to record and play back stereo audio signals while maintaining compatibility with the above-mentioned device that multiplexes a single channel audio signal with a video signal and records and plays it back. It is an object of the present invention to provide a device that can easily compensate for noise caused by discontinuity in an FM modulated audio signal.

<Description of Examples> Examples of the present invention will be described below with reference to the drawings.

The citation of the following examples does not limit the scope of the present invention, and the present invention can be modified within the scope of the claims.

Figure 2 (person) l (B) is the VT of one embodiment of the present invention
This figure shows how the tape 1 is wound around the rotary drum 2 having the rotary heads 3 and 4 by R, and the winding of the tape 1 is approximately 180° as in the conventional case.
An additional α degree (for example, about 30 degrees) is provided at the inlet of the rotating drum 2 as an overlap portion for the VTR to be wound. As a result, &) As shown in Figure 2 (B),
On the tape 1, it becomes possible to form a recording pattern 6 corresponding to the above-mentioned α degree on an extension of the entrance portion of the conventional recording pattern 5.

FIG. 3 is a diagram showing the configuration of a VTR as an embodiment of the present invention. In FIG. 3, 10 is a terminal to which a video signal such as an NTSC signal is input, and the input video signal is processed in a video signal recording processing circuit 16 to make it into a signal form suitable for recording. It will be done. For example, as shown in Figure 1, the luminance signal is FM modulated in a relatively high band
The L/chroma signal undergoes processing such as frequency conversion to a low frequency range.

The video signal processed in this manner is supplied to a mixer 26.

On the other hand, the right channel signal (Rch) of the stereo audio signal is input to the terminal 12, and the left channel signal (Lch) to the terminal 14. Input Rch
and Lch are respectively amplified by preamplifiers 18 and 20 and then added by an adder 22 to obtain a sum signal CRch+Lch. This sum signal is similar to a normal monaural audio signal. This sum signal is FM modulated by an FM modulator 24 so as to be placed between the band of the FM modulated luminance signal and the band of the low frequency converted chroma signal, and then supplied to a mixer 26. The mixed signal of the video signal and the audio signal obtained by the mixer 26 is sent to the switch 28 or the switch 3.
0. Recording is performed via the recording amplifier 34 or 36 and the R side terminal of the switch 38 or 40 in the area 5 shown in FIG. 2 by the head 42 or 44.

The Lch input to the terminal 14 is amplified by the preamplifier 20, then subjected to processing such as time axis compression and delay as described later in the time axis control circuit 46, and then FM modulated by the modulator 32. , switch 28 or switch 30, recording amplifier 34 or 36, and switch 38 or 40, head 42 or head 44 records on the area 6 shown in FIG.

Next, the configuration of the reproduction system will be explained. Head 42.44
The time axis compressed Lch reproduced from area 6 by
is the reproduction amplifier 66 or 68. (via switch 70 or switch 72) Kundonogusu Filter (BPF) 7
6 and the unnecessary A1) area component power is removed. After being demodulated by the FM demodulator 78, the time axis control circuit 46
The signal is expanded on the time axis and made into a continuous signal, which is output from the output terminal 98 as a reproduction Lch.

On the other hand, the mixed signal reproduced from area 5 is similarly transmitted to reproduction amplifier 66 or 68. “C,” via switch 70 or 72
A switch 74 converts the signal into a continuous signal. The video signal in the mixed signal is returned to its original signal form by a video signal reproduction processing circuit 94 and then outputted from an output terminal 102. (Rch +
The FM-modulated monaural audio signal of Lch) is separated by a BPF 80 and demodulated by an FM demodulator 84. The demodulated (Rch + Lch) is supplied to the subtracter 88 via a delay circuit 8G for compensating for the time change that the Lch undergoes in the time axis control circuit 46 during recording and reproduction. ) from Lch
is subtracted to obtain the reproduction Rch f. This reproduced Rch is output from the output terminal 100 via the Y side terminal of the switch 96. Now Lch from terminal 98 and Rch from terminal 100
channel, so a reproduced stereo audio signal is obtained from both of them.

Next, the dropout compensation circuit for CLch and Rch will be explained. The FM modulated signal obtained from the BPF 80 is supplied to a dropout detection circuit V'682, and by performing envelope detection etc. in this circuit 82, a pulse signal is generated during the dropout period. Dropout is F
When generated in the M modulated wave, so-called transient noise occurs in the demodulated signal even after the dropout period until the phase locked loop (PLL) in the FM demodulator tracks it. It is triggered at the falling edge of the obtained pulse signal and generates the pulse signal during the above-mentioned transient generation period. The pulse signals obtained from the dropout detection circuit 82 and the monomulti 90 are logically summed by the OR gate 92, and the dropout occurrence period and the transient occurrence period are determined by the switch 96'&X.
Connect to the side terminal. That is, at this time, dropout compensation is performed by replacing the Rch signal with the Leh signal.

FIG. 4 is a diagram showing a circuit for generating control signals for each switch shown in FIG. 3, and FIG. 5 is a timing chart showing waveforms at each part of FIG. 4 (a) to (f). Below, using FIGS. 4 and 5, each switch and time 11'i in FIG.
The operation of the axis control circuit 46 will be explained.

First, we will explain the structure of the time axis control circuit 46 in FIG. The generating oscillator, 50, is a frequency multiplier. 52.54°, 56.62, and 64 are switches, respectively, which can be appropriately switched as described later.

With this configuration, 4S, which appropriately switches the drive clock supplied to the BUD delay circuits 58, 60 between the output of the oscillator 48 and the output of the multiplier 50, makes it possible to compress or expand the time axis of the Lch. In addition, the oscillation frequency of the oscillator 48 is set to be at least twice the upper limit frequency of the audio signal to be recorded and reproduced (f,), and when driven by a clock f, which is the number of stages of the BBD, it corresponds to one field period of the video signal. Purchase the number of stages that can be read or read in a certain amount of time. On the other hand, the multiplier 50 magnification is related to the above-mentioned α degree of the angle of the overrough heave part, and in the case of approximately 30', it is 1/6 of 1800, so a frequency of 6f, which is 6 times that of the oscillator 312, is obtained. Similarly, it is a 6-multiplier, and is configured with, for example, a PLL. For example, if the upper limit frequency at which audio signals are recorded and played back is 15 KI4z, then f is 30.72 KT.
(If z t 641 is 1-84.32 KI (Z, then the number of BBD stages is 30.72 K for the NTSC signal.
) Iz/60 Hz = 512 stages.

In FIG. 5, 110 is a terminal to which the timing signal from the vertical interval 1 (lj signal) of the video signal is input during recording or playback, and in the case of an NTSC signal, it is recorded in area 5 shown in FIG. A 60Hz synchronizing signal corresponding to the period of one field of video signal is input.The input waveform is shown in FIG. Trigger on the falling edge of the pulse signal.

The outputs are Q, Q'&, and waveforms as shown in (C) and (F) of the same figure are obtained. 114 is a monomulti, which is triggered by the fall of the input pulse signal to the terminal 110,
The holding time is set to be a time equivalent to (180 degrees - α degrees) minutes. The output waveform of the monomulti 114 is as shown in FIG. 116 and 118
is an or gate, and the Q of each flip-flop 112
Output and mono multi 114 output, flip-flop 11
2 and the output of the monomulti 114 are input, and the waveforms shown in (e) and (e) of FIG.

Reference numeral 120 denotes a drive circuit for driving the switches 62 and 74 in FIG. 3, which follows the output of the flip-flop 112 during recording and follows the Q output during playback.

This is switched by switch 132. When the output is at a high level, the output is switched to the B side shown in the figure, and when the output is low level, it is switched to the F side shown in the figure.

122 is a drive circuit that drives the switches 28, 52 and 70 in FIG. 3, and according to the output of the OR gate 116,
When the output is at a high level, it is switched to the A side shown in the figure, and when it is low level, it is switched to the B side shown in the figure. Further, 124 is a drive circuit that drives switches 30, 54 and 72 in FIG.
Or game) According to the output of 11B, when the output is high level, go to C4111 shown in the diagram, and when the output is low level, go to D shown in the diagram.
switch to the side. In addition, switches 3B, 40, 56. and 64
According to an operation switch (not shown), the switch is switched to the R side shown in the figure for the 8th poem, and to the P side shown during playback.

First, the operation during recording will be explained. The Lch amplified by the heavy amplifier 20 is connected to the B channel via the R side terminal of the switch 66.
The signal is supplied to BD delay circuits 58 and 60. Looking at the timing now and considering the period t in Figure 5, switch 2
8 is connected to the A side, aO&t, and c side. Therefore,
No. 63 from the mixer 26 is amplified by recording amplifiers 34 and 36 and supplied to the heads 42 and 44. Head 42.
44 records the signal from the mixer 26 in the area 5 shown in FIG. 2 when the signals shown in FIGS. The head 42 contacts the tape and records the signal from the mixer 26 onto the tape.

Since the switch 52 is connected to the A terminal during the period t 1 , the clock of the BBDJ extension circuit 58 is driven by the output of the oscillator 48 . On the other hand, at this time the switch 54 is
Since it is connected to the terminal, the clock of the BBD delay circuit 6o is also driven by the output of the oscillator 48, and inputs Leh. The BBD delay circuit 60 has 10+1. Lch for a period of time corresponding to one field of the video signal
Accumulate exactly. Next, during the period t2, the switches 54 and 3° are connected to the D terminal, while the head 44 is connected to the D terminal as shown in FIG.
It will come into contact with the tape at the part corresponding to the α degree shown in ~. At this time, since the clock of the BBD delay circuit 60 is supplied from the D terminal of the switch 54, it becomes the output signal of the frequency multiplier 50. The period of t2 is a time corresponding to α degrees, and the frequency of the multiplier 50 is multiplied corresponding to 180 degrees and α degrees, so in the period of t2, the frequency is exactly 10+
1. The Lch stored during
M modulated. FM modulated Lcll switch 30
The signal is then amplified by the recording amplifier 36 and supplied to the video head 44, where it becomes a small signal recorded in a portion corresponding to +1 degrees α (shown in area 6 in FIG. 2).

Next, in period t3, each switch has 52.2
8 is connected to the A terminal, 54.30 is connected to the C terminal, and 62 is connected to the E terminal. Therefore, the video head 44 records the mixed signal from the mixer 26 on the tape in area 5 in FIG. DJ extension circuit 5
At the end of 1a, Lch corresponding to period 12+18 is stored in 8.

Then, during period 14, switch 52.28 is connected to the B terminal while head 42 is tracing area 6 shown in FIG. 2A. At this time, since the clock of the BBD delay circuit 58 is supplied from the B terminal of the switch 52, it becomes the output signal of the frequency multiplier 50.

The time of t4 is the time corresponding to α degrees, and the frequency of the multiplier 50 is multiplied corresponding to 180 degrees and α degrees, so that in the period of t4, exactly 12 + 18 are stored. The Lch is time-compressed, passes through the switch 64, and becomes F.
The signal is supplied to the M modulation circuit 32 and subjected to FM modulation. The FM modulated Lch passes through the B terminal of the switch 28, is amplified by the recording amplifier 34, and is recorded in the area 6 by the head 42. Then t.

The period of is exactly the same as the period of t, and after that, t
, the cycle of t4 is repeated. Therefore, the time-compressed Lch is FM modulated and recorded in area 6.

Next, the operation during reproduction will be explained. During playback, switches 38, 40, 56 and 64 are all connected to the P terminal.

From the head 42, 1. +1. The mixed signal recorded during the period , and 1. FM modulated and time-axis compressed Lch recorded during the period (= 1o) is reproduced. Further, from the head 44, the mixed signal recorded during the period 13+14 and the LC H recorded during the 1-1 period of t2 are output.
It becomes the small which reproduces ll respectively.

First, considering the period t2, each switch is switch 6
2.74 is E terminal 52.70 is A'>r:1"5 children,
54.72 is connected to the D terminal. Therefore, the FM modulated and time-axis compressed Lcb reproduced by the head 44 passes through the switch 72 and the BBr 26 to the F
The signal is supplied to the M demodulation circuit 78, demodulated, and stored in the BBD delay circuit 60 using the clock from the multiplier 5θ.

Next, considering the period t3, each switch is 62°74
is connected to the F terminal, 52.70 to the A terminal, and 54.72 to the C terminal. Therefore, the mixed signal from the head 44 is supplied to the video signal reproduction processing circuit via the switches 72 and 74, and is output from the terminal 102 after being returned to the restored country code form in which the video signal components have been separated. Also, this mixed signal was separated by BBr80 (Rch +Lc
h) is F M r5J:4.1 in circuit 84,
M-demodulated and in the delay circuit 86 (12 + 1. + 14)
It is delayed by a period of time and is supplied to a zero reducer 88. On the other hand, period 1
Since the switch 54 is connected to the C terminal, the clock of the BBD delay circuit 6o becomes the clock from the oscillator 48, and the Lch stored in the B 13 D 'Jl extension circuit 6° at From then, Lcb is expanded and restored to the original signal by time opening li1+ compared to the volume time.
will be presented. This output signal is output from a terminal 98 via switches 62 and 64, and is also supplied to the subtracter 88, and is also supplied to the X terminal of a switch 96.

At this time, the (Lch +Rch) signal from the delay circuit 86 is a signal delayed by (10+1f+12) time, so at the beginning of t3, it is the beginning signal of to. During the period t2 during recording, the head performs the
) is recorded in the area 6 of period 10.
+1. Since it is Lch, at the beginning of t8 during playback,
CLch+Rch) and Lch both become signals at the beginning of to during recording, and are supplied to the subtracter 88 (Lc
h + Rcb) and Lch are matched in time.

A subtractor 88 is provided with an input (Lc++ + R
Rch is restored by subtracting both signals from Lch) and Lch, and outputted from the terminal Zoo via the Y terminal of the switch 96.

The stereo audio signal is now being played back from the terminals 98 and 100. As described above, Lch is also output from the terminal 100 during the dropout period and the accompanying transient noise generation period.

Next, considering the period of 14, each switch is 62.74 is F
The terminals 52.70 are connected to the B terminal and 54.72 are connected to the C terminal, and the mixed signal from the head 44 is reproduced via the F terminal of the switch 74 as in the period t8, while the switch 62 is connected to the r it+ Since it is connected, the time from the BBD delay circuit 60 is expanded in the same way as the period of ta.
h is obtained, and the stereo audio signal continues to be output to the output terminals 98 and 100 as in the period 1a. On the other hand, since the switch 52.70 is connected to the B terminal, the head 42 records (1) during the 14 period.
The FM-modulated Lch audio signal corresponding to the period of ゜+t8) is sent to the FM demodulation circuit 78 via the switch 72.76.
supply to. The signal FM demodulated by the FM demodulation circuit 78 is stored in the BBD delay circuit 58 using the clock from the multiplier 50.

Next, considering the period t6, each switch has 52.70
is connected to the A terminal, 54.72 to the C terminal, and 62°74 to the E terminal. Therefore, the composite signal from head 42 is supplied to video signal reproduction processing circuit 94 and BPF 80 via switches 70 and 74. FM modulated C Lch + Rch extracted by BPF80)
is FM demodulated by the FM demodulation circuit 84, and the delay circuit 8
At 61g, the signal is delayed by a time corresponding to (1°+1.+1.) and is supplied to the adder/subtractor 88.

On the other hand, during t4, the L stored in the BBD delay circuit 5B
For channel, the switch 52 is connected to the A terminal, and the BBD
Since the clock of the delay circuit 58 is the clock from the oscillator 48, it is time-expanded compared to when it is stored in the BBD delay circuit 58, restored to the original signal, and outputted to the switch 6.
The signal is then supplied to an output terminal 98 and a subtracter 88.

At this time, (Lch+Rch) from the delay circuit 86 is (
1, +1. +1. ) time, so at the beginning of t, (Lch + Ji
ch) is the signal at the beginning of t2. Also, the signal recorded at timing t4 during recording is 12+1. Since it is the Lch of the part of , at the beginning of t6 during playback, (Lch
ch + Rch) and Lch both correspond to the beginning of t during recording, and are supplied to the subtracter 424 (
The time relationship between Lch+Rch) and Lch match. The subtracter 424 is connected to the C Lch + R supplied to the input.
(ch) and Lch to restore Rch and supply it to the output terminal 100. After that, the above steps are repeated and playback continues.

According to the above-mentioned VTR, it is possible to record and reproduce a stereo audio signal by time-compressing the Lch component of the stereo audio signal and generating the recorded RAM at the α degree of the overlamp part. Furthermore, even when a tape recorded with the device of the present invention is played back with a conventional device of this type that does not have such a function, (Lch+Rch)
monaural audio signals are played back, making it possible to maintain compatibility.

Note that it is preferable that the FM modulation circuit 32 in FIG. 3 has a carrier frequency and deviation different from those of the FM modulation circuit 24. This is because the audio signal has a band that is about six times as large as the time axis because it is compressed, and the signal after Lch demodulation is (Lcb +
This is because it requires the same dynamic range and frequency characteristics as Rch).

Also, since there is no overlap with the video signal, it is possible to use up to the i'++i range.

In the above embodiment, only dropout compensation is performed to compensate for the discontinuous portion, but the noise generation period due to the discontinuity of the Fλ1 modulation signal that occurs when switching heads is also recorded in area 6. This can be compensated by using the Lch that is present.

<Description of Effects> As explained above using the examples, according to the present invention,
While maintaining compatibility with devices that record and playback single-channel audio signals by multiplexing them with video signals, it is possible to record and playback stereo audio signals, and to playback ■Easily compensates for noise caused by discontinuity in modulated audio signals. The purpose is to obtain a device that can perform the following tasks.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the bands of each signal of a conventional VTR. FIGS. 2(A) and 2(B) show V as an embodiment of the present invention.
The winding of the tape around the rotating drum by TR is a diagram showing the shapes 'y and #. FIG. 3 is a diagram showing the structure of a VTR as an embodiment of the present invention. FIG. 4 is a diagram showing a circuit for generating control signals for each switch shown in FIG. 3. FIG. 5 is a timing chart showing the waveform of the fourth response section. 3.4, 42, 44 are heads, 5 and 6 are track portions as first and second regions, 22 is an adder, 26 is a mixer, 46 is a time axis side i circuit, and so is a band. A pass filter 86 and a delay circuit 88 are subtracters. Applicant Canon Co., Ltd. G-ku

Claims (1)

[Claims] 1) An apparatus for recording while sequentially forming a track having a first area and a second area on a recording medium using a rotary head, which outputs a left and right sum signal from a stereo audio signal. and the means to obtain it. means for obtaining a mixed signal of the sum signal and a video signal; means for recording the mixed signal in the first area with the rotating head; and means for recording the mixed signal in the first area with the rotating head; and means for recording in the second area with the head. 2) A rotating head type apparatus comprising means for recording in the second area with the head. 2) A track having the first area and the second area is sequentially formed on the recording medium with the rotating head. a device for recording while forming and sequentially tracing and reproducing the tracks; means for obtaining a left and right sum signal from a stereo audio signal;
means for obtaining a mixed signal of the sum signal and a video signal; means for recording the mixed signal in the first area with the rotary head; and means for recording the mixed signal in the first area with the rotating head; means for recording in the second area with a head; means for reproducing the mixed signal from the first area; and means for reproducing the left or right signal from the second area. , means for obtaining a reproduced video signal and a reproduced sum signal from the reproduced mixed signal, and means for obtaining a right or left reproduced signal from the reproduced sum signal and the left or right reproduced signal. .