JPS63242078A - Long time audio recorder for time lapse video tape recorder - Google Patents

Abstract

PURPOSE:To attain the recording and reproduction of a consecutive audio signal even at intermittent recording and reproduction by applying base time compression and expansion to the audio signal so as to record/reproduce the signal. CONSTITUTION:A video signal is recorded onto a video track with deframing in the unit of frames while video tape is driven stepwise intermittently at the recording and the audio signal subjected to time base compression is recorded intermitently in the unit of frames onto the audio track. The video tape is driven stepwise intermittently at reproduction to reproduce the signal, and the reproduced audio signal is subjected to time base expansion. Thus, not only the long time recording/reproducing for the video signal by the time lapse VTR is attained but also the long time recording/reproducing of the audio signal is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to long-term audio recording in a time-lapse video tape recorder.

(Prior art) In recent years, VH8 format video tape recorders (hereinafter referred to as VT
A time-lapse VTR for long-term monitoring recording using a frame recording method has been developed that is tape compatible with the VTR (denoted as R). This is achieved by recording the video signal frame-by-frame while running the video tape intermittently.
It is designed to allow long-time recording on VH8 format videotape, and this frame-by-frame recording uses a frame recording method for video signals. The advantages of the frame recording method are: (1) It is compatible with VH8 system VTRs because it records in units of frames.

(2! Only a slight modification of the conventional consumer VH8 system VTR is required for both the J mechanical part and the electric circuit part, making the system design easy and making it possible to construct an inexpensive time-lapse VTR.

etc. can be mentioned.

The above-mentioned conventional time-lapse VTR can record and play back audio signals on an audio track when used in VH8 standard and 3x modes; When used in the recording/playback mode, the audio signals recorded are fragments only during tape running. Furthermore, since the tape speed is not constant, normal audio cannot be heard even when played back.

Therefore, in the long-time recording/playback mode, no audio signals are recorded or played back.

(Problems to be Solved by the Invention) As described above, in time-lapse VTRs that run a videotape intermittently in steps and record video signals frame by frame, conventionally, long-term recording of video signals ( However, there was a problem in that it was not possible to record audio signals for long periods of time.

SUMMARY OF THE INVENTION An object of the present invention is to enable a time-lapse VTR to not only record and reproduce video signals over a long period of time, but also record and reproduce audio signals over a long period of time.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention has the following features: During recording, the video tape is intermittently stepped and the video signal is transferred frame by frame to the video track. In addition to frame-drop recording, the time-base compressed audio signal is intermittently recorded on the audio track in frame units. On the other hand, during reproduction, the signal is reproduced while the videotape is intermittently stepped, and the reproduced audio signal is expanded in time.

(Function) As mentioned above, the audio signal is recorded by compressing and expanding the time axis.
By playing back, it is possible to record and play back audio signals in sections where the tape is not running during intermittent recording and playback, and it is possible to record and play back continuous audio signals even during intermittent recording and playback. Ru.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a recording system according to an embodiment, and FIG. 2 is a block diagram showing an example of a specific configuration of main parts of the circuit shown in FIG. 1. Further, FIG. 3 is a block diagram showing the overall configuration of the reproduction system of one embodiment, and FIG. 4 is a block diagram showing an example of the specific configuration of the main parts of the circuit shown in FIG. 3.

FIG. 5 shows the cylinder head assembly used in the time-lapse VTR of this embodiment, and FIG. 6 shows the head width and head step. The cylinder head assembly shown in FIG. 5 is used in a consumer @i-1:1 VTR, and is not a special one.

In addition, in FIG. 5, εP1. EP2. SP1゜SF
3 is a rotating head for video signals, AFMl, AFM
2 is a rotary head for audio signals.

(1) Here, intermittent recording of video signals and audio signals will be explained.

(2) First, an outline of intermittent recording will be explained with reference to FIGS. 7 to 10.

In the time-lapse VTR of this embodiment, the videotape is moved intermittently in steps by intermittent driving of the capstan motor. The frame-sampled video signal linked to this step running is recorded on the video track, and the time-axis compressed audio signal described later is recorded at A.
Frames are recorded on the FM (Ht-Fl) track.

FIG. 7 shows a timing chart for intermittent recording to be compatible with the VH8 3x mode tape format.

The capstan motor is synchronized with the video switching pulse and is driven after a time Tt from the fall of the video switching pulse. acceleration period.

After passing through a series of operations including a constant speed section and a deceleration section, it stops, and the videotape is fed one frame. A video signal is recorded on a video tape (frame dropping) during a period (one frame) when a video signal recording gate pulse is at a low level while the capstan motor is being driven. Also, during the same period when the audio (AFM) signal recording gate pulse is at low level, the FM-modulated audio (
AFM) signals are deep recorded on videotape.

FIG. 8 shows a head trace when intermittent recording is performed as described above. Further, the tape pattern is shown in FIG. Recording of video signals is EPl and EP2 in Fig. 5, audio (AF
M) Signal recording is performed using AFM A1 and AFM in Figure 5.
Use an A2 head.

What should be noted here is the phase difference T2 between the video switching pulse and the AFM head switching pulse shown in FIG. This T2 is determined by the mounting angle of the AFM bed and video head in FIG. 5, and is selected so that T2 is as small as possible. This is to ensure the linearity of both the video signal recording pattern and the AFM signal recording pattern in intermittent recording. Figure 10 is T2
This shows the AFM signal recording pattern when securing the linearity of the video signal recording pattern is given priority when T2 is large.If T2 is large, the linearity of the AFM signal recording pattern deteriorates if priority is given to securing the linearity of the video signal recording pattern.

Therefore, T2 should be chosen as small as possible, for example 4
Set within ~5ISeC.

(2) Next, a configuration for performing intermittent recording of audio signals as described above will be described with reference to FIGS. 1 and 2.

The audio signal recording circuit shown in FIG. 1 is configured to handle monaural audio signals for long-term monitoring and recording purposes. The circuit in FIG. 1 is a monaural circuit as described above, and includes a time axis compression circuit 20 surrounded by a broken line, an L channel (hereinafter referred to as LCH) and an R channel for audio signals.
LcH distributed to channels (hereinafter referred to as RaH)
*RCH distribution has the same circuit configuration as a conventional Hi-Fi VTR, except that it includes a circuit 21. Therefore, so that it can be used as a conventional Hl-Fi VTR, a stereo input/output circuit, a time axis compression circuit, and an Lc
A circuit configuration in which a bypass circuit is provided and the H-RCH distribution is switched by a switch is also possible.

First, the circuit shown in FIG. 1 will be explained. In the figure, an audio signal for recording input to an input terminal 11 is amplified by an amplifier 12 and then set to a constant amplitude by an automatic gain control circuit 13.

This gain control output is led to an audio mute circuit 16 via a switch 14 and an amplifier 15. And if audio mute is off. , is supplied from the output terminal 17 to an audio output circuit (not shown) and monitored.

The gain control output is further subjected to noise removal by a noise reduction circuit 18, and then to a pre-emphasis circuit 1.
9 to the time axis compression circuit 20. and,
The time axis is compressed by this time axis compression circuit 20, Lc
The H-RcH distribution is divided into LoH and RCH by a circuit 21.

Thereafter, the audio signals of each channel are amplitude limited by limiters 22.23, and then FM modulation circuits 24.2
FMIDI is performed at 5. Each modulated output is then added by an adder 26 and then supplied to amplifiers 28 and 29 through a gate circuit 27 for a period defined by the AFM recording gate pulse. After being amplified by the amplifiers 28 and 29, the signals are applied to the heads AFMA1 and AFMA2 through switches 30 and 31, and are recorded on AFM tracks on a video tape (not shown).

Next, the time axis compression circuit 20 and LCH"R1 shown in FIG.
'H distribution will be explained with reference to FIG. 11 regarding the configuration of the circuit 21. Incidentally, FIG. 11 is a time chart showing the process of time axis compression of the audio signal, distribution to Lc+ and Rc+-+, and recording to the AFM track.

Methods of time axis compression include methods using analog delay elements such as BBD and COD, analog/digital converters (hereinafter referred to as A/D converters), and digital/analog converters (hereinafter referred to as 'D/A converters'). Although methods using a memory IC (referred to as a converter) and a memory IC are known, FIG. 2 shows an example using an A/D converter, a D/A converter, and a memory IC.

In FIG. 11, the audio signal input during the period ta to [1 is converted into a digital signal by the A/D converter 41 and then stored in the memory 43 via the I/D port 42. Similarly, the audio signal input during the period tl to t2 is A
After being converted into a digital signal by the /D converter 42, the I/D converter 42 converts the signal into a digital signal.
It is stored in the memory 44 via the D port 42.

Next, t6 to t! stored in the memory 43! The audio signal for the period t2-t3 (approximately 33.31860)
The signal is read out from the memory 43 and supplied to the D/A converter 45 via the I10 port 42. After being converted into an analog signal by this D/A converter 45, it is recorded on the LcH AFM track on the video tape. Similarly, the audio signal for the period t1 to t2 stored in the memory 44 is
It is read from the memory 44 during the period t2 to t3 (approximately 33.3+e sec) and is sent to the D/D via the I10 port 42.
A converter 46 is supplied. After being converted into an analog signal by this D/A converter 46, the A of the videotape is converted into an analog signal.
It is recorded in RaH of the FM track.

Here, since is j2<tl-to-t2-tl, the audio signal of period to=t1 (or t1-t2) is t
The time axis is compressed from t-1o (or t2-ts) to t3-t2 and recorded on LcH (or RcH) of the AFM track.

In this way, the signal for the continuous period from ta to t2 is converted from ta to t2.
T! divided into a signal for a period of and a signal for a period from t1 to t2,
By compressing the time axis and recording on the LCH and RCH AFM tracks, the time compression rate can be reduced and the frequency band for the signal can be widened.

Thereafter, the audio signals input during the period t2 to t5 are similarly time-base compressed and stored in the AFM track. In this case, the audio signal for the period t2 to t4 is stored in the memory 47 and recorded on the La+ AFM track. On the other hand, t4
The audio signal for a period of ~ts is stored in memory 48 and RO
recorded on the M AFM track.

In addition, in FIG. 2, 49 is a memory 43°44.47
．． This is an address counter that outputs 48 address designation data (ADR8). 50 is memory 43.44.4
This is a memory control circuit that switches between write mode W and read mode W of 7.48. Reference numeral 51 denotes a clock generation circuit that generates a clock serving as a reference for the operation of various circuits.

A system control circuit 52 controls the operation of the entire VTR, and a timing control circuit 53 controls the operation timings of various circuits under the control of the system control circuit 52.

In addition, the above memory 43.44 or memory 47.48
are set, for example, by dividing the memory space on the same memory.

In the manner described above, the input audio signal is completely recorded on the AFM track.

(2) Next, intermittent playback of video signals and audio signals will be explained.

(2) First, an outline of intermittent playback will be explained with reference to FIGS. 12 and 13.

The principle of intermittent playback of video signals is based on the conventional VH8 system VTR.
This is similar to the clean slow playback described above, and is performed by repeating a series of operations such as field still playback, feeding one frame of the tape, and field still playback using a W azimuth head by intermittent driving of the capstan motor.

To reproduce the audio signal during intermittent playback, the AFM track on which the above-mentioned time-axis compressed audio signal is recorded is played back in conjunction with the intermittent step running of the video tape by the intermittent drive of the capstan motor. This is to extend the time axis.

As shown in Figure 9, the head trace when reproducing an intermittently recorded tape pattern
Shown in Figure 2. To reproduce the video signal, the SP in FIG.
1, EP1 and EP2 heads are used. When the capstan motor is stopped, field still reproduction of the pattern of the head EP1 recorded on the video tape is performed using the head SP1 and the head EP1. While the videotape is being stepped by the capstan motor drive, the head E
P2 is used to prevent noise.

Figure 12 shows the video signal and AF when slow tracking is adjusted so that a good envelope of the video signal can be obtained both during still playback and during step running of the videotape.
The reproduction envelope of the M signal is shown. The audio signal is A
The part of the FM playback envelope shown by α in Figure 12 is frame sampled (the opposite of frame dropping, frame playback).
After A/D converting this and storing it in memory, the time axis is expanded. FIG. 13 shows a timing chart during intermittent playback.

Audio (AFM) signal reproduction is performed using AFMAl and A in Figure 5.
Uses FM A2 head.

(2) Next, a configuration for performing the intermittent reproduction 6 of the audio signal as described above will be explained with reference to FIGS. 3 and 4.

The circuit shown in FIG.
It is almost the same as a VTR.

In FIG. 3, the head (AFMAI), (λFMA
The audio signals reproduced in 2) are sent to each switch 30.
．． After being applied to amplifiers 61 and 62 via 31, the signal is converted into a continuous signal by a switch 63.

Of these, the LOH audio signal is filtered through the bandpass filter 63.
After passing through the FM limiter 64 and having its amplitude limited by the FM limiter 64,
l [FM demodulated by modulator 65. This demodulated output is supplied to a hold amplifier 67 through a low-pass filter 66, and dropout interpolation is performed according to the outputs of a dropout detection circuit 68 and a hold time circuit. Rc+
The audio signal is also passed through the bandpass filter 70. FM limiter 71° FM demodulator 72. Hold amplifier 74. Similar processing is performed by the dropout detection circuit 76 and hold time circuit 76.

The outputs of the hold amplifiers 67 and 74 are converted into continuous signals by the LCH/RCH rearrangement circuit 77 and then sent to the time axis expansion circuit 7.
8, the time axis is extended. This time axis expanded output is passed through a de-emphasis circuit 79 to a noise reduction circuit 80.
The noise component is removed. This noise-removed output is sent to the switch 14° amplifier 15. The audio output is provided and monitored via the audio mute circuit 16.

Next, the configurations of the LcH-RcH rearrangement circuit 77 and time axis expansion circuit 78 shown in FIG. 4 will be explained with reference to FIG. 14. The fourteenth factor is a time chart showing the process of frame sampling the audio signal from the AFM trazok, rearranging it by La+ and RaH, expanding the time axis, and outputting it as an audio signal.

In Fig. 14, among the signals demodulated from the AFM LOH reproduction signal, the period filta during driving of the capstan motor is
~ts (approximately 33.3+e sec) (7) IS minute e
7 L/- After sampling, the A/D converter 81
and convert it into a digital signal. This conversion output is then provided to memory 83 via I10 port 82 for storage. Also, among the signals demodulated from the AFM RaH reproduction signal, period 111 during driving of the capstan motor
After frame sampling the part from to to t1, A/
The signal is supplied to a D converter 84 and converted into a digital signal. After this, this conversion output is passed through the I10 port 82 to the memory 8.
5 and stored.

Next, the audio signal for the period t6"-tl stored in the memory 83 is stored in the period t2"-t3 (approximately 33.3 m 5ec
) is read out from the memory 83 and supplied to the D/A converter 86 via the I10 port 82. And this D/
After being converted into an analog signal by the -A converter 86, it is supplied to the de-emphasis circuit 79 shown in FIG. Similarly, t8 to 1. The audio signal for the period t2 to t3 (approximately 33,3ai sec')
The signal is read out from the memory 85 and supplied to the D/A converter 86 via the I10 port 82. -And this D/
After being converted into an analog signal by the A converter 86, it is supplied to the de-emphasis circuit 79.

Here, t1-t6<t2-t1=t! −j
2, so the period ta~t! The audio signal of is tl-1,
The time axis is expanded from t2-tt (or tl!-t2).

Thereafter, the audio signals reproduced during the period t3 to t4 are similarly subjected to LcH-RcH rearrangement processing and time axis compression processing. In this case, the LOH audio signal is stored in memory 87 and the RCH audio signal is stored in memory 88.

In addition, in FIG. 4, 89 is a memory 83°85.87
．． This is an address counter that outputs 88 address designation data (ADR8). 90 is memory 83.85.8
This is a memory control circuit that switches between write mode W and read mode W of 7.88. Reference numeral 91 denotes a clock generation circuit that generates a clock serving as a reference for the operation of various circuits.

A timing control circuit 92 controls the operation timing of various circuits under the control of the system control circuit 52.

The memories 83, 85 or 87, 88 are set, for example, on the same memory by dividing the memory space.

Note that the above I10 port 82. Memory 83°85.87
．． 88. Address counter 89. Memory control circuit 90. The clock generation circuit 91.degree. timing control circuit 92, etc. may also be used as those shown in FIG. 2 above.

As described above, according to this embodiment, by compressing and expanding the time axis of the audio signal and recording and reproducing it, it is possible to record and play back the audio signal without intermittent recording or recording, or even the audio signal in the section where the tape is not running during playback. Recording and reproduction are possible, and continuous recording and reproduction of audio signals can be performed even in intermittent recording and reproduction. In addition, although the tape running speed during intermittent recording and playback is not constant, the AFM track (Audio Hi-Fi
By recording frames on a track), wow and flutter can be suppressed, and it is also possible to record audio with time compression in terms of bandwidth.

Although one embodiment of the present invention has been described above in detail, the present invention is not limited to this embodiment, and various other modifications can be made without departing from the gist of the invention. Of course.

[Effects of the Invention] As described above, since the long-time audio recording of the time-lapse VTR according to the present invention is based on the frame recording method, VH
It is tape compatible with S-video tapes, and requires only minor modifications to conventional consumer Hi-Fi VHS video in both the mechanical and electrical circuit sections, making system design easy and allowing for the construction of inexpensive time-lapse VTRs. It is possible to record and reproduce audio signals over a long period of time without sacrificing the advantages of the conventional time-lapse VTR.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of a recording system in one embodiment, FIG. 2 is a block diagram showing an example of a specific configuration of the main parts of the circuit shown in FIG. 1, and FIG. 3 is a block diagram showing an example of an embodiment. FIG. 4 is a block diagram showing an example of the specific configuration of the main parts of the circuit shown in FIG. 3. FIG. 5 is a block diagram showing the overall configuration of the playback system in the example. FIG. 6 is a diagram showing the head width and head stage, FIGS. 7 to 10 are diagrams for explaining the recording process of one embodiment, and FIG. 11 is a diagram showing the cylinder head assembly. FIG. 2 is a time chart for explaining the operation of the circuit shown in FIG. 2, FIG. 12 and FIG. It is a time chart for explanation. 20-...Time axis compression circuit, 2"l"・Lcn'RC
H distribution is circuit, 41.81.84...A/D converter, 42.82...I10 board, 43.44.47° 48.83.85.87.88...Memory, 45° 4
6.86...D/A converter, 49.89...Address counter, 50.90-...Memory control circuit, 51.91-...Clock generation circuit, 52...System control 0- Circuit, 53.92...timing control circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 5 Figure 814 Figure 10

Claims (1)

[Scope of Claims] In a time-lapse video tape recorder that records a video signal frame by frame while intermittently running a videotape in steps, a time-base compression means for compressing the time-base of an audio signal recorded on the videotape; , an audio recording means for intermittently recording the time axis compressed output of the time axis compressing means on the audio track of the videotape in frame units; An audio reproduction means for reproducing a time axis compressed output of an audio signal; and a time axis expansion means for expanding the time axis of the reproduction output of the audio reproduction means to obtain an audio signal having a time axis before recording. A long-term audio recording device for time-lapse video tape recorders.