JPH0793716B2 - Intermittent magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intermittent magnetic recording / reproducing apparatus which is used for monitoring by performing recording / reproduction for a long time by intermittent recording.

[Conventional technology]

In a rotary head helical scan system VTR (video tape recorder), a video signal is recorded as a still image at a rate of one sheet every few seconds by intermittent feeding of magnetic tape, and a maximum of 240
The intermittent magnetic recording / reproducing device (called time-lapse VTR) that performs long-time recording / reproducing for about 480 hours is widely used for monitoring purposes at financial institutions.

An example of this intermittent recording time-lapse VTR is disclosed in, for example, JP-A-58-62985.

However, since the time-lapse VTR is an intermittent recording, the method of recording and reproducing the audio signal on the linear track generally used for the audio recording of the VTR cannot be used, and the linear track described above can be used only in the incidental continuous recording mode for about 2 to 12 hours. It only has a voice recording / playback function that uses, and could not record / playback voice in the intermittent recording mode of about 24 to 480 hours actually required for monitoring.

[Problems to be solved by the invention]

Since the above-mentioned prior art uses a linear track for voice, it is inconvenient that the voice signal cannot be recorded by the intermittent recording system in which running and stopping of the magnetic tape are intermittently repeated, and the voice recording function is lacking. .

An object of the present invention is to provide an intermittent magnetic recording / reproducing apparatus capable of recording / reproducing high-quality continuous audio information even in an intermittent recording system, and having video compatibility with a time-lapse VTR without a conventional audio recording function. Especially.

[Means for solving problems]

The above object is to provide means for writing the audio signal on the magnetic tape with the audio rotary head having an azimuth angle different from that of the video rotary head by time-compressing the audio signal with the semiconductor memory even when the magnetic tape is stopped. This is achieved by forming a recording track in a guard band area existing between one video signal recording track and an adjacent video signal recording track.

[Action]

The audio signal is time-axis compressed, and the compressed audio signal is recorded in the guard band area existing between the video signal recording tracks while the magnetic tape is stopped through the audio-specific rotary head. This operation is repeated for each intermittent feed at a predetermined time interval, and continuous audio can be recorded on the audio recording track one after another even with intermittent feed.

Since the rotary head for audio has a predetermined step with the rotary head for video, it is possible to form the video track and the audio track in one stopped state. In addition, since the azimuth angle of the audio head is recorded differently from that of the video head, compatibility with the conventional time-lapse VTR can be made possible and mutual interference between the video signal and the audio signal can be achieved even if tracking deviation occurs. almost none.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an intermittent magnetic recording / reproducing apparatus according to an embodiment for explaining the entire recording / reproducing operation. Reference numeral 1 is a magnetic tape, 2 is a rotary head 3 for video, and a rotary head 4 for audio. Rotating drum mounted on a tower, 5 is a capstan motor, 6
Is a capstan control circuit, 7 is a drum control circuit for controlling a drum motor (not shown) for rotating the rotary drum 2, 8 is a servo circuit, and 9 is a folding noise when the input audio signal IN is digitized. The low-pass filters LPF ₁ , 10 and 19 for preventing this are switches that are switched by a recording mode signal REC that becomes “H” during recording and becomes “L” during reproduction, and the black circle side indicates the recording mode. 11 is an A / D (Analogue to Dig) for digitizing the output ADIN of the changeover switch 10.
ital) converter, 12 is a gate for controlling the output data of the A / D converter to the data bus DATA BUS, 13 is an address counter CNT for designating the address of the compression / expansion memory 14, and 15 is the intermittent magnetic recording according to the present invention. Control signals W, CLK, Re, REC for each part in order to perform intermittent recording and reproduction of video and audio signals according to a mode command from the system control (abbreviated as syscon, not shown) of the playback device (including mechanism) Controller, which supplies D / A (D
igital to Analogue) converter, 17 is a low-pass filter LPF ₂ for removing unnecessary frequency components generated by sampling, 18 is an FM modulator for frequency-modulating the compressed audio signal and writing it in the audio rotary head 4. Reference numeral 20 is an FM demodulator for frequency-demodulating the signal obtained from the rotary head 4 for reproduction during reproduction to obtain a compressed demodulated sound signal SIG, and 21 is an S demodulator.
Low-pass filter LPF ₃ to prevent the generation of aliasing noise when digitizing IG ₃ , 22 is a low-pass filter LP to remove unnecessary frequency components generated by sampling
F ₄ and 23 are inverters for inverting the read / write (read / write) control signal W of the memory 14.

FIG. 2 shows a top view of the rotary drum 2 of FIG. 1, and FIG. 3 shows a front view. In the apparatus shown in FIG. 1, the rotary head for image 3,
3'has the same azimuth angle gap, the rotary head 4 for audio has a different azimuth angle from 3,3 ', and the video heads 3 and 3'are at the same height (zero step), the video head The voice head 4 has a predetermined step d as shown in FIG. FIG. 4 is a diagram showing a recording pattern recorded on the rotary drum 2. The magnetic tape 1 is intermittently moved by one track pitch P in the direction of an arrow 25 to form one video signal recording track V ₁ . Adjacent video signal recording track V ₂
An audio signal recording track A ₁ is formed in the card band portion between and. In this example, the head widths of the three heads 3, 3'and 4 are selected to be approximately half of the track pitch P, and the step d is also selected to be approximately half of P so that the audio signal recording tracks A ₁ and A ₂ are provided in the card band portion. ... is formed. Also
The V ₁ and A ₁ tracks are created with the magnetic tape 1 stopped.

Next, the operation of this apparatus will be described with reference to the block diagram of FIG. 1, the recording pattern diagram of FIG. 4 and the signal waveform diagram of each part of FIG. 1 shown in FIG.

The capstan control circuit 6 controls the servo circuit to intermittently drive the capstan motor 5 so that a video signal recording track and an audio signal recording track are formed at one track pitch at a predetermined time interval (rotation attached to the motor 5 The frequency generator signal CFG indicating the information is counted to obtain movement information corresponding to one track pitch), and the video recording head V 3 is used to form the video recording track V ₁ while the magnetic tape 1 is stopped. Form track A ₁ . Next, the video head 3 is intermittently fed corresponding to one track pitch.
(Or 3 'may be) V _2, the records A ₂ voice head 4, thereafter repeated. During playback, it is driven similarly intermittently, and the video signal is played while the video rotary heads 3 and 3'having the same azimuth angle are stopped on the video track (for example, V ₁ ) of the magnetic tape 1, and the magnetic tape is used for audio. The rotary head 4 reproduces an audio signal from an audio recording track (for example, A ₁ ).

Next, the operation at the time of recording the audio signal will be described. Input voice signal
IN is low-pass filter LPF _{1 with} 9 and recording status (REC “H”)
Is converted into a digital signal (4 bits in the embodiment) by the A / D converter 11 through the changeover switch 10. As shown in FIG. 5, the clock CLK has a low frequency ( _SL ) while the read / write control signal W is “H”, and the audio signal passing through the gate 12 is stored in the memory through the data bus DATA BUS.
Written at 14 predetermined addresses. The controller sets the W to "H" at a predetermined intermittent driving cycle T, outputs the Re pulse to initialize the address counter 13, and then sets the magnetic tape 1 to 1
Move the track pitch and stop. Then (T
The period W of −τ) is kept at “H”, and the audio signal is written in the memory 14 at the low speed clock ( _SL ). Then, by setting the period W of τ immediately before the next intermittent drive to “L”, the recorded audio signal is read from the memory, time-axis compressed, and sent to the D / A converter 16 via DATA BUS. Supplied. That is, at the trailing edge of W, the address counter 13 is reset and initialized again, and the clock CLK is compressed at a high frequency ( _SH ) to a compression rate T / τ.

Here, the compression ratio T / τ = _SH / _SL . Compressed digital audio signal is converted to analog signal DAOUT by D / A converter 16.
And is frequency-modulated by the FM modulator 18 through LPF _2.
It becomes DRV (frequency modulation wave) and is supplied to the voice head 4 through the changeover switch 19 (REC state). The inverted signal of W from the inverter 23 is input to the FM modulator,
The recording current is supplied to the head 4 only during the period of τ.
τ is a period corresponding to one field of the image and is equal to the vertical synchronizing signal period V, which is 1 / 59.94 (seconds) in the NTSC system.

The formation of the video recording pattern and the audio recording pattern will be described in time series as follows. In the stopped state of the magnetic tape, the video signal is _first recorded on the video recording track V ₁ by the rotary head 3 immediately before the period τ in FIG. 5, and immediately after that, the compressed audio signal is recorded on the voice track A ₁ by the rotary head 4 during the period τ. Immediately after that, the magnetic tape corresponding to one track pitch is intermittently fed to form V ₂ and A ₂ . The recording timing (the rising or falling point of W) may be created with reference to a signal DTP corresponding to the rotational phase of the rotary head (output from the tack detection means attached to the rotary drum 2, not shown).

The video and audio recording timings can have various relationships other than the above-described method. For example, if a video recording pattern is created after a lapse of a period of about T after the audio recording pattern is created and the diameter magnetic tape 1 is intermittently fed, the time of the video and audio during playback depends on the application. The relationship can be made more natural, and each image can be recorded as a still image like an album, and can be suitable for use as a home video file in which audio corresponding to each is recorded.

Next, using the signal waveform diagram of each part at the time of voice reproduction of FIG.
It will be described that the compressed audio signal is expanded and decoded into the original continuous audio. REC is "L" because it is during playback. When the rotary head 4 is on the upper side of FIG. 4A ₁ , the compressed audio signal from the head is frequency-demodulated by the FM demodulator 20 through the change-over switch 19 (white circle side) and the baseband SIG
And is converted into a digital signal by the A / D converter 11 through the LPF ₃ and the changeover switch 10. For FM modulation / demodulation, the emphasis and pre-emphasis technologies that are normally used for video signals are used as needed. When the head 4 is on A ₁ , a Re pulse is output from the controller 15 to initialize the address counter 13, and at the same time the period W of τ is set to “H”, so that the compressed audio signal passing through the gate 12 is One field is stored in the memory 14 through the DATA BUS with the high-speed clock _SH (the clock CLK is in the state of the high-speed clock _SH because W is "H"). Immediately after that, when W becomes "L", the magnetic tape 1 is moved intermittently by one track pitch, and at the same time, the Re pulse is output and the low-speed clock _SL (because W is "L") is output from the first address. Read and DATA B
The decompressed and restored audio signal is input to the D / A converter 16 through the US. By repeating the above operation in the cycle of T, the compressed audio signal is expanded as shown by DAOUT in FIG. 6 and the original recorded audio is continuously decoded. The DAOUT signal is passed through the LPF ₄ to remove the unnecessary signal during the period of τ during writing in the memory 14, and the output signal OUT is output. Note that a normally used analog N that compresses the dynamic range of the input audio signal, records it, and expands it during playback
The dynamic range can be expanded by using (Noise Reduction) technology as needed.

The device uses a tape for VHS type 2-hour recording mode,
Compressed audio is recorded at intervals of 4 (seconds), and the compression rate is 240 times, which enables recording for 480 hours.

Next, as the embodiment of the present invention, the head width of the rotary head is
An example in which the magnetic tape utilization efficiency is improved even if there is a tracking deviation by making w ₁ and w ₂ wider than approximately half of the track pitch P in the figure, the front view of the rotary drum in FIG. 7 and the recording pattern diagram in FIG. I will explain based on. Head here
Although 3,3 'and 4 are not exactly the same as those in FIG. 3, the same reference numerals are used for convenience of explanation because they correspond to those in FIG. 3 (for other symbols such as V ₁ and A _{1 in} FIG. 8). The same).

If the head width of the video heads 3 and 3'is w ₁ , the head width of the audio head 4 is w ₂ and the step between them is d as shown in FIG. 7, the recording pattern of FIG. 8 is obtained (V ₁ The pattern located in front of is A ₀ ). As an example of numerical values, in the case of the VHS system, if w ₁ = 30 μm, w ₂ = 30 μm, = 29 μm (P = 58 μm), an overwritten portion of 1 μm occurs between the tracks as shown in FIG. That is, the actually recorded tracks V ₁ , A ₁
Has a track width of 29 μm, and the head width is set wider than these track widths.

It is recorded on the magnetic tape shown in FIGS. 9 to 12 below that the mutual interference between the video and the audio in the overwritten portion between the tracks A ₀ , V ₁ , A ₁ , and V ₂ can be almost eliminated by the present invention. This will be described with reference to the frequency allocation diagram of the recorded audio signal.

First, in the area of pattern A ₀ (A ₁ is the same) in FIG. 8 that does not overlap with the video pattern, 3.9M shown by dotted line 61 in FIG.
There is only an FM-modulated audio signal centered at Hz and containing no low frequency components. Second, in the overwriting area of pattern A ₀ and pattern V ₁ , the video signal is 3.9M as shown by the solid line in FIG.
An FM-modulated luminance signal 63 centered at Hz and a low-frequency converted color signal 64 centered at 629 KHz are superposed and recorded. Since the audio signal recorded immediately before is in the high frequency range, it is almost attenuated by the video signal as shown by the score 62. Third, the solid line FIG. 11 in a region not overlapping with the voice pattern in the pattern V ₁ 6
Only video signal exists like 3,64. Fourth, in the overwriting area of the pattern V ₁ and the pattern A ₁ , the audio signal 61 is recorded on the video signal as shown in FIG. 12, and similarly the luminance signal is almost attenuated to 65, but Since the signal is in the low range, considerable information is left.

As described above, by using the wide head, the guard band is not formed even by the track turning at the time of recording, and even if the tracking deviation occurs at the time of reproduction, the signal information of the user is not lost, and As shown in Fig. 12 and Fig. 12, there is a feature that it can be configured so that interference from adjacent ones can be almost ignored together with the difference in azimuth angle (in this example, set to 30 ° with respect to -6 ° of the image head). is there.

Further, from the above recording patterns, the magnetic tape of the conventional image only can be reproduced by the apparatus of the present invention, the magnetic tape of the present invention can be reproduced by the conventional apparatus, and mutual compatibility can be ensured.

Next, as an embodiment of the present invention, an example will be described in which loss of audio information during writing of compressed audio onto a magnetic tape is compensated. Thirteenth
The figure is a part of a block diagram showing an embodiment of the present invention.
.About.44 are gate circuits, 45 and 47 are memories, 46 and 48 are address counters, and 49 is the same as FIG. The operation of FIG. 13 will be described with reference to the signal waveform diagram of each portion during recording of FIG. 14 and the recording pattern diagram of FIG. The input audio signal ADIN passes through the A / D converter 11 and the gate circuit 41, and as in the case of FIG. 5, the low-speed clock _SL is used as the “H” period clock CLK _A of the memory control signal W _A.
Is supplied to the address counter CNT _A 46 and the memory MEM _A 45
Memorized in. Operation of the memory MEM _B 47 is the same. The falling time of W _A is set to 0 (second) as the time reference, and the intermittent drive cycle is 4 (second). 4~t compressed audio signal from the memory MEM _{B 2}
Τ _B period (W _B is “L”) is read. Since the input voice signal during the recording operation is recorded in another memory MEM _A in the voice pattern A ₁ in FIG. 15, in the case of FIG. Thus, there is no loss of τ _B period.

Address counter CNT _B 48 of the memory MEM _B input speech to -0.2 is reset at -0.2 seconds (sec) to 4 (in seconds) is stored in the MEM _B. Next, at 4 (seconds), a reset pulse of Re _B is output and the pattern of A ₁ in Fig. 15 shows -0.
2 (s) to 4 signals up (in seconds) is read from the time memory MEM _B of tau _B, the compression ratio 240 in which recorded the (patterned on
It has been compressed to 1/240 due to the doubling, and is shown as the time axis in Fig. 15). On the other hand when the address counter CNT _A 46 of the memory MEM _A 3.8 (seconds) is reset 3.8 seconds to 8
The input voice signal at the time point (second) (including the period of τ _B ) is stored in the memory MEM _A and is compressed and recorded in the pattern A ₂ after intermittent feeding. Since there is an overlap period in writing and reading in two systems of memory, as shown in Fig. 14, the gate circuit
41 to 44 are controlled by A _A , D _A , A _B , and D _B signals, and W
Is creating overlapping information DAOUT for writing to the voice head during the "H" period.

Next, the operation of reproducing an audio signal without any loss will be described based on the signal waveform diagrams of the respective parts of FIG. 13 during the reproduction of FIG. The compressed audio signal IN reproduced from the audio head passes through the A / D converter 11 and the gate circuit to reset the address counter once, and then is written in the memory by the high-speed clock _SH , and immediately thereafter, the address counter is reset and initialized. DAOU is read from the memory with the low-speed clock _SL
Output to T. The point of 0 (second) on the time axis of FIG. 15 is taken as the reproduction reference t ₃ . Since the voice signal is recorded for 0.2 seconds extra in pattern A ₁ , t ₃ −0.1 (second) to t ₄ (second)
Up to W _A as “H” (t ₄ = t ₃ +3.9 (sec)) Memory MEM _A
High-speed clock is read, the audio signal recording time -0.1 seconds ～3.9 seconds in making the W _A from t ₄ to t ₅ "L" to D _A "H" is output from the DAOUT to. And performs write and read similarly using memory MEM _B signals from t ₃ + 4-0.1 (in seconds) until t ₅ seconds from the next pattern A _2, recording time 3.9 seconds ～7.9 (seconds) The audio signal of is output from DAOUT, and it is possible to reproduce the audio signal without any loss as shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, the audio signal is time-axis-compressed and written on the magnetic tape by the rotary head when the magnetic tape is stopped. Since a means such as making the azimuth angle of the rotary head provided for audio different from that for video is used, there is no mutual interference with the video, compatibility with the conventional time-lapse VTR, and a high level with no margin for tracking deviations. A continuous voice recording / playback function of sound quality can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of an intermittent magnetic recording / reproducing apparatus for explaining the entire recording / reproducing operation of the present invention, FIG. 2 is a top view of the rotary drum of FIG. 1, and FIG. 3 is a rotary drum of FIG. FIG. 4 is a recording pattern diagram by the rotary head of FIG. 2, FIG. 5 is a signal waveform diagram of each portion during recording, FIG. 6 is a signal waveform diagram of each portion during reproduction, and FIG. FIG. 8 is a front view of a rotary drum according to an embodiment of the invention, FIG. 8 is a recording pattern diagram of FIG. 7, FIG. 9, FIG. 10, FIG. 11 and FIG. 12 are voice recording allocation diagrams, and FIG. 14 and 16 are signal waveform diagrams of respective parts, and FIG. 15 is a block diagram according to the embodiment of FIG.
It is a recording pattern figure of a figure. 2 ... Rotating drum, 3,3 '... Video head, 4 ... Audio head, 5 ... Capstan motor, 9,17,21,22 ... Low pass filter, 11 ... A / D converter, 16 ... D / A converter , 1
4,45,47 ... Memory, 15,49 ... Controller, 18 ... FM modulator, 20 ... FM demodulator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Mikami 1410 Inada, Katsuta City, Ibaraki Prefecture, Tokai Plant, Hitachi, Ltd. (56) References JP-A-58-62985 (JP, A) JP-A-61 -237205 (JP, A) JP-A-55-58807 (JP, A) JP-A-61-74483 (JP, A) JP-A-60-175210 (JP, A) JP-B-59-53603 (JP, B2) )

Claims (1)

[Claims] 1. A means for intermittently repeating running and stopping of a magnetic tape at predetermined time intervals, a rotary head for recording a video signal, and a video signal for one field during a stop period as one video recording track. In an intermittent magnetic recording / reproducing apparatus having means for recording on a tape, a memory for time-axis compression / expansion of an audio signal every predetermined time, and an audio signal stored in the memory based on a first clock, The time-compressed audio signal is intermittently read out every predetermined time as a time-axis compressed audio signal based on the second clock having a higher frequency than the first clock, and the start portion of the time-compressed audio signal read from the memory and the previous time are read. Memory control means for controlling writing and reading to and from the memory so that the end portion of the time-compressed audio signal overlaps with the time-axis-compressed audio signal. Has a gap of an azimuth angle different from that of the video signal recording rotary head for recording on a magnetic tape, and is set wider than the audio signal recording track width, and with the video signal recording rotary head. An audio signal recording rotary head having a predetermined step between them, and a means for frequency-modulating the time-axis-compressed audio signal from the memory and supplying the audio signal recording rotary head to the audio signal recording rotary head. When traveling is stopped, a time-axis compressed audio signal together with a video signal is recorded on a magnetic tape so that a video signal recording track and an audio signal recording track are alternately formed for each track. Intermittent magnetic recording / reproducing device.