JP3196645B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for digital image signals, and more particularly to a current analog VTR.
The present invention relates to a magnetic recording / reproducing apparatus compatible with the magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art At present, as a home image signal recording / reproducing apparatus, an analog VTR using an 1/2 inch wide oxide tape has been put to practical use.

On the other hand, the practical use of digital broadcasting as next-generation TV broadcasting is being promoted. For example, MPEG (Movi
2. Description of the Related Art There has been known a system for performing high-efficiency digital compression encoding using an ng Picture Experts Group) method and broadcasting the data through a satellite or a coaxial cable.

[0004] These digital broadcasting systems are described in the Journal of the Institute of Television Engineers of Japan, Vol. 47, No. 4 (19).
93), pp. 486-503.

[0005]

Recently, these digital TV broadcasts have been put to practical use and implemented in a form mixed with analog TV broadcasts. However, in a conventional analog VTR, these digital image signals are converted to digital signals. Recording and playback could not be performed as is.

An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of recording and reproducing digital compression-encoded image and audio signals such as digital TV broadcasts as digital signals while being compatible with existing analog VTRs. Is to provide.

[0007]

In order to achieve the above object, a magnetic recording / reproducing apparatus according to the present invention records an analog image signal or a digital information signal on a track formed on a magnetic tape in an oblique direction and records the signal. A rotating drum equipped with a first magnetic head group for recording and reproducing analog image signals and a second magnetic head group for recording and reproducing digital information signals; means for generating a first reference signal from the synchronizing signal in the means for generating a second reference signal from the color subcarrier frequency signal of the analog image signal, the
Means for generating a third reference signal inside the apparatus, means for generating a first switching signal corresponding to the rotation phase of the rotating drum for switching an operating magnetic head in the first magnetic head group, and a rotating drum A means for generating a second switching signal for switching the operating magnetic head in the second magnetic head group in accordance with the rotation phase of the second magnetic head group; and a servo means for controlling the rotation phase and rotation speed of the rotating drum. The means is arranged so that the first reference signal and the first switching signal are synchronized when recording an analog image signal, and the second reference signal and the first switching signal when reproducing the analog image signal. When the digital information signal is recorded and reproduced, the rotation phase of the rotating drum is controlled so that the third reference signal and the second switching signal are synchronized.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention. Where 1a, 1b,
2a and 2b are magnetic heads, 5 is a rotating drum, 6 is a magnetic tape, 11, 21 and 31 are input terminals, 12 is an analog image recording signal processing circuit, 22 is an analog audio recording signal processing circuit, and 32 is a digital recording signal processing Circuit, 13, 1
5, 17, 23, 25 and 27 are changeover switches, 14, 2
4 is a recording amplifier, 16 and 26 are reproduction amplifiers, 18 is an analog image reproduction signal processing circuit, 28 is an analog audio reproduction signal processing circuit, 38 is a digital reproduction signal processing circuit,
9, 29 and 39 are output terminals, 41 is a recording servo circuit,
42 is a reproduction servo circuit, 51 is an analog / digital selection circuit, and 52 is an analog / digital discrimination circuit.

First, the operation at the time of recording an analog image signal will be described. At the time of recording, the changeover switches 15, 2
5 are connected to the [R] side.

Referring to FIG. 1, an analog image signal input from an input terminal 11 is subjected to FM modulation of a luminance signal and a low-frequency conversion of a color difference signal in an analog image recording signal processing circuit 12, and they are added. It is converted into an analog image recording signal SR1. On the other hand, the analog audio signal input from the input terminal 21 is subjected to FM modulation of the left / right or positive / sub 2 channel audio signals in an analog audio recording signal processing circuit 22, and the analog audio recording signal added thereto Converted to SR2. FIG.
(A) and (B) show examples of the frequency bands of the analog image recording signal SR1 and the analog audio recording signal SR2, respectively.

Here, the analog / digital selection circuit 5
When an analog image signal is selected as a signal to be recorded by the switch 1, the changeover switches 13 and 23 are respectively connected to the [A] side by the output control signal CR1, and the analog image recording signal SR1 and the analog audio recording signal SR2 are The magnetic head 1 is connected via the recording amplifiers 14 and 24, respectively.
a, 1b and 2a, 2b. The recording system servo circuit 41 sets the rotation speed R of the rotary drum 5 to the first rotation speed R1, and sets the traveling speed V of the magnetic tape 6 to the first traveling speed V1.
Control to 1. Note that the drum rotation speed R1 is set to the same value as the frame frequency of the analog image signal to be recorded.

FIG. 3 shows an example of the recording pattern at this time. First, an analog audio recording signal SR2 is recorded on the magnetic tape 6 by the magnetic heads 2a and 2b, and an analog audio track 62a having a track width Tw2 is recorded.
62b is formed. Next, the analog image recording signal SR1 is superimposed on the analog audio tracks 62a and 62b by the magnetic heads 1b and 1a, and the track width T
The w1 analog video tracks 61b and 61a are formed. Tp1 is a track pitch. For example, if the drum diameter of the rotary drum 5 is 62 mm, its rotation speed R1 is 29.97 rps, which is the same as the frame frequency of the analog image signal, and the running speed V1 of the magnetic tape 6 is 33.35 mm / s, the track pitch Tp1 is 58 mm. Become. At this time, the track width Tw1 of the analog video tracks 61b and 61a is 40 mm to 58 mm.
mm, and the track width Tw2 of the analog audio tracks 62a and 62b is set to 20 mm or more. In the case of an analog image signal having a frame frequency of 25 Hz, if the drum rotation speed R1 is 25 rps and the tape running speed V1 is 23.39 mm / s, the track pitch Tp1 is 49 mm.

Next, the operation at the time of recording a digital image signal will be described.

In FIG. 1, an input terminal 31 has an MPEG
A digital image and audio signal which has been compressed and encoded by a high-efficiency compression method is input to the digital recording signal processing circuit 32. The digital recording signal processing circuit 32 performs formatting processing such as interleaving, addition of an error correction code and a synchronization signal, and blocking. It is encoded (modulated) and converted into a digital recording signal SR3.

Here, assuming that the same oxide tape as used for analog recording is used for the magnetic tape 6, the recording rate of the digital recording signal SR3 can be increased to about 20 Mbps with a high-performance tape having an increased holding power. . At this time, the transmission rate of the input signal can be secured up to about 15 Mbps even in consideration of the redundancy caused by the formatting processing in the digital recording signal processing circuit 32. On the other hand, MP
The transmission rate of the video signal and the audio signal which are highly efficient compression-coded by the EG-2 system is about 10 Mbps at the maximum,
Therefore, it is possible to record the digital image signal and the audio signal on the same oxide tape as the analog recording. As described above, the present invention has been made in view of the fact that a digital image signal can be recorded with a bandwidth close to an analog image signal due to the development of a high-efficiency image compression technique.

In the above example, the actual input rate is about 10 Mbps for the maximum input rate of about 15 Mbps.
And there is room for about 5 Mbps. In this case, the extra data may be used to record a signal for special reproduction.

The analog / digital selection circuit 51
When a digital image signal is selected as a signal to be recorded by the digital camera, the changeover switch 23 is connected to the [D] side by the output control signal CR1, and the digital recording signal SR is output.
3 is supplied to the magnetic heads 2a and 2b via the recording amplifier 24. At this time, the changeover switch 13 is also connected to the [D] side by the control signal CR1, and the magnetic heads 1a, 1b
Is not supplied with anything. The recording servo circuit 41 receives the control signal CR1 from the analog / digital selection circuit 51 and changes the rotation speed R of the rotary drum 5 to the second rotation speed R2.
Then, the traveling speed V of the magnetic tape 6 is controlled to the second traveling speed V2. The drum rotation speed R2 is set to a constant rotation speed regardless of the frame frequency of the digital image signal to be recorded.

The recording rate of the digital recording signal SR3 is recorded at a substantially constant recording rate determined by the recording density of the magnetic tape 6, irrespective of the transmission rate of the input digital image and audio signals. The maximum input rate is determined from this recording rate. If the input rate is lower than this, dummy data is added, or as described above, data for special reproduction is added to make the recording rate almost constant. Record. For example, when the magnetic tape 6 is a high-performance oxide tape, as described above, the recording rate is about 20 Mbps, the maximum input rate is about 15 Mbps, and digital image and audio signals of up to 15 Mbps can be recorded. .

FIG. 4 shows an example of a recording pattern of the digital signal. A digital recording signal SR3 is recorded on the magnetic tape 6 by the magnetic heads 2a and 2b, and digital signal tracks 63a and 63b having a track pitch Tp2 are formed. For example, if the drum diameter of the rotary drum 5 is 62 mm, the rotation speed R2 is 30 rps, and the running speed V1 of the magnetic tape 6 is 16.67 mm / s, the track pitch Tp2 is about 29 mm.

Next, the operation at the time of reproduction will be described. At this time, the switching switches 15 and 25 are respectively connected to the [P] side. The analog / digital determination circuit 52 determines whether the signal recorded on the magnetic tape 6 is an analog image signal or a digital image signal. Then, the changeover switches 17 and 27 are controlled by the output control signal CP1 to switch the processing system of the reproduced signal. Similarly, the reproduction system servo circuit 42 receives the control signal CP1 and changes the rotation speed R of the rotary drum 5 to the first rotation speed R1 or the second rotation speed R1.
And the running speed V of the magnetic tape 6 is controlled to the first running speed V1 or the second running speed V2.

First, an operation at the time of reproducing an analog image signal will be described.

As described above, when the signal recorded on the magnetic tape 6 is determined as an analog image signal by the analog / digital determining circuit 52, the magnetic heads 1a and 1b
Signal SP reproduced by the
1 is input to the analog image reproduction signal processing circuit 18 via the changeover switch 17, the reverse processing of the analog image recording signal processing circuit 12 is performed, and the original baseband analog image signal is output from the output terminal 19. You. On the other hand, the signal SP2 reproduced by the magnetic heads 2a and 2b and amplified by the reproduction amplifier 26 is supplied to an analog audio reproduction signal processing circuit 28 via a changeover switch 27, and is converted into an original analog audio signal. 29.

Next, the operation at the time of reproducing the digital image signal will be described.

When the analog / digital discriminating circuit 52 determines that the signal recorded on the magnetic tape 6 is a digital image signal, the output control signal CP1 connects the switching switches 17 and 27 to the [D] side. The signal SP3 reproduced by the heads 2a and 2b and amplified by the reproduction amplifier 26 is input to the digital reproduction signal processing circuit 38 via the changeover switch 27. In the digital reproduction signal processing circuit 38, the digital recording signal processing circuit 32
, And restores the original digital image and audio signals, which are output from the output terminal 39.

In the case of an analog image signal, the head for recording and reproducing the field image is a magnetic head 1a.
Or 1b, but in the case of a digital image signal,
As shown by the track pair numbers in FIG. 4, for example, it may be necessary to form a pair with the magnetic heads 2a and 2b. In this case, there is a problem that the servo circuit of the rotating drum 5 cannot be dealt with by the conventional analog image signal drum servo circuit.

FIG. 5 is a block diagram showing an example of a drum servo circuit according to the present invention. Here, the drum servo portions in the recording servo circuit 41 and the reproduction servo circuit 42 are shown together. In the figure, 411 is a vertical synchronization signal detection circuit, 412 is a 1/2 frequency divider circuit, 413 is a frequency divider circuit, 414, 415, and 427 are changeover switches,
21 is a speed servo circuit, 422 is a phase servo circuit, 42
3 is an addition circuit, 424 is a motor driver, 425 is a drum motor, and 426 is a waveform shaping circuit.

First, a case where an analog image signal is recorded will be described. At this time, the changeover switch 414 is connected to the [R] side, and the changeover switches 415 and 427 are connected to the [A] side.

The synchronization signal Sync separated by the analog image recording signal processing circuit 12 is input to a vertical synchronization signal detection circuit 411, where a vertical synchronization signal V.Sync is detected. This vertical synchronizing signal V.Sync is frequency-divided by で in the 分 frequency dividing circuit 412, and the reference signal Ref is passed through the changeover switches 414 and 415.
Is input to the phase servo circuit 422.

The drum motor 425 is a motor driver 42
4 to rotate. At this time, the drum motor 4
The rotation frequency of the drum motor 425 is detected and input to the speed servo circuit 421. The speed servo circuit 421 outputs an error signal between the input rotation frequency of the drum motor 425 and a predetermined frequency. The error signal is input to the adding circuit 423.

On the other hand, a so-called tack pulse corresponding to the rotation phase of the drum motor 425 is detected and input to the waveform shaping circuit 426. The waveform shaping circuit 426 generates a head switching signal SW30Hz for switching the magnetic heads 1a and 1b and a head switching signal SW30Hz-A for switching the magnetic heads 2a and 2b based on the tack pulse, and the head switching signal SW30Hz selected by the switch 427 is generated. It is input to the phase servo circuit 422. The phase servo circuit 422 compares the input reference signal Ref with the phase of the drum motor,
The error signal is output to the addition circuit 423. Addition circuit 4
23 adds the input error signals from the speed servo circuit 421 and the phase servo circuit 422, and the added two error signals are fed back to the motor driver 424. In this way, the rotation of the drum motor 425 is controlled so as to be phase-synchronized with the reference signal Ref.

FIG. 6 is a waveform diagram showing the timing of the operation at the time of the analog recording. Here, (A) is a vertical synchronization signal V.Sync, (B) and (D) are reference signals Ref, (C),
(E) is a head switching signal SW30 Hz. Thus, 1
Depending on the output state of the 1/2 frequency dividing circuit 412, the reference signal Ref becomes indeterminate whether it is (B) or (D). As a result, the head switching signal SW30Hz also becomes indeterminate (C) or (E). That is, if the "L" period of the head switching signal SW30Hz is the recording period of the magnetic head 1a and the "H" period is the recording period of the magnetic head 1b, the even field of the image signal is recorded by the magnetic head 1a. It is uncertain whether the data is recorded by the head 1b, but there is no problem in the case of an analog signal. However, in the case of digital, there is a problem,
The present invention was born.

The phase difference τ in the figure indicates the phase difference between the position of the vertical synchronizing signal and the head switching point, for example, 6.5.
H (H is the period of the horizontal synchronization signal).

At the time of reproduction, a signal separated by the analog image reproduction signal processing circuit 18, for example, a color subcarrier frequency signal
Fsc is frequency-divided by the frequency dividing circuit 413, and a signal having a frequency equal to 1/2 of the vertical synchronization signal V.Sync at the time of recording is output.
An output signal of the frequency dividing circuit 413 is selected by a changeover switch 414 connected to the [P] side and a changeover switch 415 connected to the [A] side, and is input to the phase servo circuit 422 as a reference signal Ref. Thereafter, the same operation as during recording is performed, and the drum 5 is phase-locked.

The operation of controlling the rotation of the drum 5 during recording and reproduction of an analog image signal has been described above.

Next, the operation of the drum servo circuit shown in FIG. 5 for recording and reproducing digital image signals will be described.

In the case of digital, the same operation is performed during recording and reproduction. That is, the reference signal S.Ref is output from the digital recording signal processing circuit 32 or the digital reproduction signal processing circuit 38. The reference signal S.Ref is a signal equal to the rotation frequency of the drum 5 and is directly input to the changeover switch 415. The changeover switch 415 is connected to the [D] side, selects the reference signal S.Ref, and selects the reference signal S.Ref.
22. On the other hand, the head switching signal SW30Hz-A is input to the phase servo circuit 422 via the changeover switch 427 connected to the [D] side. Thereafter, the drum 5 is locked to the reference signal S.Ref as in the case of recording / reproducing an analog signal.

FIG. 7 is a waveform diagram showing the timing of the operation at the time of digital recording and reproduction. Here, (A) is the reference signal S.Ref, and (B) is the head switching signal SW30Hz-A. In this way, the digital recording signal processing circuit 32 or the digital reproduction signal processing circuit 38 supplies the reference signal S.Re.
f is a pulse format similar to the vertical synchronizing signal V.Sync of an analog image signal, the pulse cycle is not a field cycle, but a frame cycle equal to the rotation cycle of the drum 5, and changeover switches 415 and 427 are added. Accordingly, digital recording and reproduction can be supported by sharing a conventional drum servo circuit.

Incidentally, the servo circuit of the recent analog VTR is considerably softwareized and incorporated in the system microcomputer together with the peripheral hardware, and the changeover switches 415 and 427 as hardware
May not be added.

FIG. 8 is a block diagram showing an example of a drum servo circuit corresponding to such a case. In the figure, 429 is an inverter, 429 is a changeover switch, 43
Reference numeral 0 denotes a phase difference detection circuit, and the same reference numerals as those in FIG. 5 denote the same components. Here, at the time of analog recording / reproduction, the operation is exactly the same except for the position of the changeover switch 415.

During digital recording / reproducing, the changeover switch 41
4 is connected to the [R] side irrespective of recording and reproduction, and the changeover switch 415 is connected to the [D] side. Digital recording signal processing circuit 32 or digital reproduction signal processing circuit 38
The reference signal S.Ref output from the
Is input to the vertical synchronization signal detection circuit 411. The vertical synchronization signal detection circuit 411 converts the input frame pulse into a field pulse by pulse interpolation, and apparently detects the signal V.Sync, which is the same as the vertical synchronization signal of the analog image. This vertical synchronizing signal V.Sync is frequency-divided by で in a 分 frequency dividing circuit 412, and is input to a phase servo circuit 422 as a reference signal Ref via a changeover switch 414. The phase difference detection circuit 430 detects the phase difference between the reference signal S.Ref and the reference signal Ref, and controls the changeover switch 429 according to the result.

On the other hand, the waveform shaping circuit 426 generates the head switching signal SW30Hz and SW30Hz-A. At this time, the phase of the head switching signal SW30Hz is set to the same phase as the head switching signal SW30Hz-A (analog signal recording / reproducing). At the time, there is a phase difference corresponding to the mounting angle difference between the magnetic heads 1a and 1b and the magnetic heads 2a and 2b). Then, the in-phase signal and the signal inverted in phase by the inverter 428 are selected by the changeover switch 429 controlled by the phase difference detection circuit 430, and input to the phase servo circuit 422 as the head changeover signal SW30Hz. Hereinafter, the drum 5 is synchronized with the reference signal S.Ref by the same operation.

FIG. 9 is a waveform diagram showing the timing of the operation at the time of digital recording and reproduction. Here, (A) is a reference signal S.Ref, and (B) is a pulse-interpolated vertical synchronizing signal.
V.Sync, (C), (F) are reference signals Ref, (D),
(G) shows the head switching signal SW30 Hz, and (E) and (H) show the head switching signal SW30 Hz-A. As described above, the fact that the reference signal Ref becomes indeterminate between (C) and (F) depending on the output state of the 1/2 frequency dividing circuit 412 is similar to that during analog recording / reproducing, but corresponds to that state. Then, the head switching signal SW30Hz inputted to the phase servo circuit 422 is also (D),
By performing the inversion control as shown in (G), the head switching signal SW30Hz-A becomes the reference signal S.H. as shown in (E) and (H).
The phase is always constant with respect to Ref.

Although the inverter 428 and the changeover switch 429 are depicted in the form of hardware in FIG. 8, they can actually be implemented by software, and the phase difference detection circuit 430 can also be implemented by software. Therefore, the only hardware external to the servo circuit incorporated in the system microcomputer is the changeover switch 415.

[0045]

As described above, according to the present invention,
The digital compression-encoded image signal can be recorded and reproduced on a common recording medium with a common head configuration while maintaining compatibility with the current analog VTR. Moreover, the servo circuit can share the conventional analog circuit without any change.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram illustrating an example of a recording frequency spectrum of an analog image signal and an analog audio signal.

FIG. 3 is a diagram showing a track pattern on a magnetic tape when an analog image and an audio signal are recorded.

FIG. 4 is a view showing a track pattern on a magnetic tape at the time of recording a digital image and an audio signal.

FIG. 5 is a block diagram showing a configuration example of a drum servo circuit according to the present invention.

6 is a waveform chart showing operation timings of the drum servo circuit shown in FIG. 5 at the time of analog recording.

7 is a waveform chart showing operation timings of the drum servo circuit shown in FIG. 5 at the time of digital recording and reproduction.

FIG. 8 is a block diagram showing another configuration example of the drum servo circuit according to the present invention.

9 is a waveform chart showing operation timings of the drum servo circuit shown in FIG. 8 during digital recording and reproduction.

[Explanation of symbols]

 1a, 1b, 2a, 2b: magnetic head, 5: rotating drum, 41: recording servo circuit, 42: reproducing servo circuit, 411: vertical synchronization signal detection circuit, 412: 1/2 frequency dividing circuit, 413: minute Peripheral circuits, 414, 415, 427, 429: changeover switches, 422, phase servo circuits, 426, waveform shaping circuits, 428, inverters, 430, phase difference detection circuits.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-147805 (JP, A) JP-A-8-65633 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 15/473

Claims (3)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for recording an analog image signal or a digital information signal on a track formed on a magnetic tape in an oblique direction, and reproducing the recorded signal. A rotating drum equipped with a first magnetic head group for performing recording and a second magnetic head group for recording and reproducing the digital information signal; a means for generating a first reference signal from a synchronization signal in the analog image signal; Second from the color subcarrier frequency signal of the analog image signal
Means for generating a third reference signal inside the apparatus, and means for switching an operating magnetic head in the first magnetic head group in accordance with the rotation phase of the rotary drum. Means for generating a first switching signal; means for generating a second switching signal for switching an operating magnetic head in the second magnetic head group in accordance with the rotation phase of the rotary drum; and rotation of the rotary drum. Servo means for controlling a phase and a rotation speed. The servo means, when recording the analog image signal, synchronizes the first reference signal and the first switching signal with each other. When reproducing the image signal, the second reference signal is synchronized with the first switching signal. When recording and reproducing the digital information signal, the third reference signal and the second switching signal are synchronized. Faith So that the issues are synchronized,
A magnetic recording / reproducing apparatus for controlling a rotation phase of the rotating drum. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein when the analog image signal is recorded / reproduced by the first magnetic head group, the second magnetic head group controls the deep magnetic layer of the magnetic tape. A magnetic recording / reproducing apparatus characterized in that an analog audio signal is superimposed on a recording and reproducing section. 3. The magnetic recording / reproducing apparatus according to claim 1, wherein the frequency of the second reference signal is approximately 29.97 (30/30).
1.001) Hz, the frequency of the third reference signal is set to approximately 30 Hz, and the servo circuit sets the rotation speed of the rotary drum to approximately 29.97 rps during reproduction of the analog image signal, A magnetic recording / reproducing apparatus characterized in that the recording / reproducing of an information signal is performed at approximately 30 rps.