JPH02161602A - magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording/reproducing device that is provided with a recording magnetic head and a reproducing magnetic head separately. , relates to a magnetic recording/reproducing device for reproduction.

[Conventional technology]

In a helical scan type magnetic recording and reproducing device that uses a rotating magnetic head to record and reproduce video signals,
Video signals are recorded and reproduced as one-channel signals, and the rotating magnetic head is used for both recording and reproduction. In such magnetic recording and reproducing devices, video signals are generally recorded as analog signals.

On the other hand, when a video signal is digitized and recorded and played back, the digital video signal with a large amount of information is divided into multiple channels, and each channel is recorded and played back as an information signal with a small amount of information. Magnetic recording and reproducing devices have been proposed (for example, Japanese Patent Laid-Open No. 56-77
Publication No. 912).

In such a magnetic recording/reproducing apparatus, a magnetic head is provided for each channel, and the information signals of the divided channels are simultaneously recorded and reproduced by the respective magnetic heads. The reproduced information signals of each channel are combined to obtain the original digital video signal.

On the other hand, in magnetic recording and reproducing devices, it is naturally required to record more information on a certain amount of recording medium, that is, to increase recording density. In particular, as mentioned above, magnetic recording and reproducing devices that record and reproduce multi-channel digital video signals are expensive! ! Densification is required. To this end, conventional efforts have been made to improve the performance of magnetic heads and improve the recording/reproducing characteristics of magnetic heads on recording media. is planned.

Furthermore, in order to improve the recording and reproducing characteristics, it is also necessary to optimize the electromagnetic conversion efficiency (recording efficiency, reproducing efficiency) of the magnetic head. However, if the magnetic head is structured to have an optimal recording efficiency, the reproducing efficiency will decrease, and if the magnetic head is constructed to have an optimal reproducing efficiency, the recording efficiency will decrease. Therefore, instead of using a magnetic head for both recording and playback,
A recording magnetic head and a reproducing magnetic head are provided separately,
A method has been proposed in which the recording efficiency of the recording magnetic head is optimized and the reproducing efficiency of the reproducing magnetic head is optimized to improve the overall recording and reproducing efficiency.

[Problem to be solved by the invention]

By the way, since the magnetic head records information signals while being in contact with the recording medium and not moving, the contact portion with the recording medium gradually wears out as the magnetic head is used for a long time. Due to this wear, the gap depth of the magnetic spatula 1z decreases, and along with this, the performance of the magnetic spatula 1z deteriorates. In other words, as the gap depth decreases, the inductance/space of the magnetic head decreases, which changes the gain and phase characteristics of the reproduction system, which were initially adjusted to be optimal, and causes a deterioration of the reproduction image quality. Become. In addition, when the head life reaches the end of its life, which is usually said to be several thousand hours due to wear,
It becomes impossible to record or reproduce normally with this magnetic head.Furthermore, the optimum recording current of the magnetic head also depends on the gap depth. Therefore, when the gap depth decreases, the optimum recording current for this magnetic head also changes. Therefore, even if an optimal recording current is initially set for the magnetic head, as the gap depth decreases, this recording current becomes an over-recording current, resulting in a decrease in recording efficiency and a decrease in the reproduction output level. As a result, the S/N deteriorates j3,2 and the reproduced image quality deteriorates -'.

Furthermore, the magnetic throat may be damaged by an unfair attack, and in such a case, reliable recording or reproduction becomes impossible.

Abnormal conditions such as breakage and characteristic deterioration of the magnetic head as described above naturally occur in the magnetic recording and reproducing apparatus equipped with the above-mentioned recording magnetic head and reproducing magnetic head. n deteriorates and becomes unrecordable or reproducible.

Conventionally, when this situation occurs, the magnetic recording re-temperature device is set to a non-use state and the abnormal magnetic field is removed. However, this work is time-consuming and does not allow the magnetic field to be replaced or cleaned. There was a problem in that it was not possible to quickly respond to gutter abnormalities, making it very inconvenient to use in the event of such a malfunction.

Also, we do not know when such an abnormal state of the magnetic head will occur, so we do not know when to record it. If the problem occurs during 1, or if the magnetic head is abnormal or recording is performed without knowing τ, the desired screen may not be recorded well or at all, -2 and (5 times 4, The purpose of the invention is to eliminate such problems and to quickly respond to abnormalities in the magnetic head.
Is it possible to always perform good recording and playback? [Means for Solving the Problems] In order to achieve the above object, the present invention provides a magnetic recording head and a magnetic reproducing head. In a magnetic recording/reproducing device, when recording, if the recording magnetic field is abnormal,
Recording mode selection means for using the magnetic head for recording instead of the magnetic head for recording, and the case where the electromagnetic disk for δeQ is selected as the recording head, and the case where the magnetic disk for δeQ is selected as the recording head, A KWtM equalization means is provided whose recording equalization characteristics are switched depending on whether the front or rear end is selected.

The present invention also provides a rotary head type magnetic recording and reproducing device for recording and reproducing digital video signals, in which the above-mentioned recording magnetic head is selected as the recording head and the above-mentioned reproducing magnetic head is selected as the recording head. If selected, means for changing the timing of supplying the digital video signal to the recording head with respect to the rotational phase of the rotary cylinder, and the recording and timing of the control signal to the magnetic chip. Set up.

Furthermore, the present invention has the following features:
, When playing, the magnetic field for playback is always 3%.
In place of the reproducing magnetic head of 1, 2 and 2, use the recording head as the reproducing head. A re-equalization means whose re-equalization characteristics are switched depending on whether the re-equalizing head is iKW or when the recording magnetic field is selected.
There are two.

Also, this invention! , j2.7' A magnetic recording and reproducing device with a rotary head for recording.

To playback, use the throat and 17 to turn on the above playback magnet! When selecting 1' and when selecting the above-mentioned recording magnetic head, the company must perform phase synchronization with the rotational phase of the rotating cylinder. Means for increasing the timing of the reproduction head switching signal generated by the magnetic tape, and means for changing the timing of the parfon/D-ru signal reproduced from the magnetic tape are provided.

[Effect]

During recording, if an abnormality occurs in the recording magnetic head due to breakage or characteristic deterioration, the control signal generating means generates a control signal to replace the abnormal recording magnetic head.
The reproducing magnetic head is selected as the recording head, and information signals are thereby recorded. The recording equalization means is configured such that equalization characteristics can be switched, and when a recording magnetic head is selected as the recording head, the recording current of the recording magnetic head has frequency characteristics optimal for recording. , when a reproducing magnetic head is selected as the recording head, separate equalization characteristics are set so that the recording current of the reproducing magnetic head has frequency characteristics optimal for recording.

As described above, even if the recording magnetic head becomes abnormal, the information signal can be recorded satisfactorily.

Furthermore, there is a positional difference between the recording magnetic head and the reproducing magnetic head on the rotating cylinder. When the recording head selection means switches the recording head from the recording magnetic head to the reproducing magnetic head, it shifts the timing of supplying the information signal to be recorded to the reproducing magnetic head by an amount corresponding to the position difference, and also shifts the timing of supplying the information signal to the reproducing magnetic head by an amount corresponding to the position difference. The recording timing is also shifted in the same way.

As a result, the tracks for the digital video signal on the magnetic tape are formed correctly, the recording operation is performed in the same way as when the recording magnetic head is normal, and the recording magnetic head is not connected to the recording head on the magnetic tape. A track pattern similar to that when selected as is obtained.

Furthermore, during reproduction, if an abnormality occurs in the reproducing magnetic head due to damage or characteristic deterioration, the control signal generating means generates control No. 13, and a corresponding recording head is used instead of the abnormal reproducing magnetic head. A magnetic head is selected as a reproducing head, and the information signal is thereby reproduced. The reproduction equalization means is configured to be able to switch equalization characteristics, and when a reproduction magnetic head is selected as the reproduction head, the reproduction equalization means is configured so that the reproduction information signal from the reproduction magnetic head has optimal frequency characteristics. Furthermore, when a recording magnetic head is selected as the reproducing head, separate equalization characteristics are set so that the reproduced information signal from the recording magnetic head has optimal frequency characteristics.

As described above, even if the reproducing magnetic head becomes abnormal, the information signal can be reproduced satisfactorily.

Further, there is a positional difference between the recording magnetic head and the reproducing magnetic head on the rotating cylinder. When the reproducing head selection means switches the recording head from the reproducing magnetic head to the recording magnetic head, the timings of the reproduced control signal and the reproducing head switching signal are shifted by an amount corresponding to the positional difference. As a result, the reproducing head correctly reproduces and scans the tracks on the magnetic tape, and the heads are switched in accordance with the scanning timing of the magnetic tape by the reproducing head, so that a correct digital video signal can be obtained.

〔Example〕

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, in which 1 is an input terminal for a video signal, 2 is an A/
D conversion/channel division circuit, 3゜4 is shuffling/
ECC encoding circuit, 5゜6 is a modulation circuit, 7.8 is a recording equalization circuit, 9 and 10 are switch circuits, 11 to 14 are recording amplifiers, 15 to 22 are rotary transformers, 23 to 3o
31 to 34 are recording magnetic heads; 35 is a switch circuit;
~38 is a magnetic head for reproduction, 39~42 is a preamplifier,
43.44 is a switch circuit, 45.46 is a reproduction equalization circuit, 47.48 is a demodulation circuit, 49.50 is a deshuffling/FCC decoding circuit, 51 is a D/A conversion/channel synthesis circuit, 52 is a video signal output Terminal, 53 is a rotating cylinder, 54 is a magnetic tape, 55 is a capstan motor,
56 is a capstan motor servo circuit, 57 is a cylinder motor servo circuit, 58 is a control head, 59 is a tack head, and 60 is a control signal generator.

In this embodiment, it is assumed that a video signal is digitized, divided into two channels, recorded on a magnetic tape, and reproduced.

In the figure, a magnetic tape 54 is wound around the outer periphery of a rotating cylinder 53 in a substantially tso' spiral shape, and travels in the direction of arrow A by the rotation of a capstan motor 55 controlled by a capstan motor servo circuit 56. Further, the rotating cylinder 53 rotates in the direction of arrow B due to rotation of a cylinder motor (not shown) controlled by a cylinder motor servo circuit 57.

The rotating cylinder 53 has four recording magnetic heads 31 to 31.
34 and four reproducing magnetic heads 35 to 38 are provided. The recording magnetic heads 31 and 32 are arranged close to each other, and the recording magnetic heads 33 and 34 are also arranged close to each other, so that the recording magnetic heads 31 and 33 are arranged close to each other.
, the recording magnetic heads 32 and 34 are arranged at an angular interval of 180°. Similarly, the reproducing magnetic head 35
and 36, and the reproducing magnetic healds 37 and 38 are arranged close to each other, respectively, and the reproducing magnetic healds 35 and 37 and the reproducing magnetic nodules 36 and 38 are arranged at an angular spacing of 1800, respectively. In addition, here, the magnetic heads 31, 37, 3
3.35 and magnetic helads 32°, 38, 34, and 36 are respectively arranged at an angular interval of 45° in one inclination, but regarding the arrangement relationship between the recording magnetic head and the reproducing magnetic head. is not limited to this.

The recording magnetic heads 31 to 34 are not used only for recording, but are used for reproduction when the reproduction magnetic heads 35 to 38 are in an abnormal state such as damage or characteristic deterioration. Similarly, the reproducing magnetic heads 35 to 38 are also
When the recording magnetic nodes 31 to 34 are in an abnormal state, they are used for recording. For this purpose, the rotating cylinder 53
Further, switch circuits 23 to 30 are provided. These switch circuits 23-30 are a, b, and c, respectively.

It has a d terminal. The a terminal of the switch circuit 23 is connected to the recording magnetic head 31, and the switch circuit 11.
24, 25, and 26 terminals are connected to each recording head 33,
32, 34, switch circuits 23, 24, 25
．． 26 b terminals are each low retransistor 15.16.1
7.18 is connected. Also, S-Itsu Thousand Circuits 27
．． The a terminals at 28 and 29° 30 are connected to the preamplifier 39.
40. 41 and 42, and the b terminals are connected to reproducing magnetic heads 35, 37 and 36, 38, respectively. Further, the C terminal of the switch circuit 23 and the C terminal of the switch circuit 28 are connected, and hereinafter, the switch circuits 24 and 27,
The C terminals of the switch circuits 25 and 30 and the switch circuits 26 and 29 are connected to each other. Furthermore, a control signal (No. 3) is supplied from a control signal generator 60 to the d terminals of these switch circuits 23 to 30, and depending on this control signal, between terminals a and b, between terminals b and c, between terminals c and a, The switch circuits 23 to 30 are arranged like this, and the control is closed.
By controlling these with the i(δ number generator 60, the recording magnetic heads 31 to 34 can be used only for recording, and the reproducing magnetic heads 35 to 38 can be used only for reproduction.
Furthermore, the recording magnetic heads 31 to 34 can also be used for reproduction, and the reproduction magnetic heads 35 to 38 can also be used for recording. By providing magnetic heads for reproduction, each head gap value (
Gap depth) and head inductance value can be set independently as shown in Figure 2, thereby optimizing recording efficiency and playback efficiency, reducing drive voltage of recording amplifiers 11 to 14, and increasing playback output. can be calculated.

Next, the operation of this embodiment will be explained.

First, during recording, the capstan motor servo circuit 56
The capstan motor 55 is controlled to rotate at a constant speed,
The magnetic tape 54 runs at a constant speed.

Further, the rotating cylinder 53 is rotated at a constant speed by a cylinder motor servo circuit 57 at a period equal to one frame of the video signal to be recorded. The rotational phase is set so that the tack pulse representing the rotational phase of the rotary cylinder 53 obtained by the tack head 59 and the frame pulse of the video signal to be recorded have a predetermined phase relationship.

This video signal is input from input terminal l, A/D converted and
The large capacity digital data is digitized by the channel division circuit 2 and divided into two channels of digital data in accordance with the recording rate of the magnetic recording/reproducing apparatus. These digital data are supplied to shuffling/ECC encoders 3 and 4, respectively. In the shuffling/EC encoding circuit 3.4, distributed processing is performed using memory so that the order of data is disorganized, and furthermore, an error correction code E CC is applied to the distributed digital data.
ode ) is added. The output digital data of the shuffling/ECC encoding circuit 3.4 is modulated by a method suitable for recording in each modulation circuit 5.6, and then the recording current is modulated by a recording equalization circuit 7.8 to have an optimal frequency characteristic. The signal is processed as follows and supplied to the switch circuit 9, ]0.

Here, when the recording magnetic spatula)'31=34 is normal, the switch circuit B23''26 closes between the a and b terminals by the control signal supplied from the control signal generator 60 to the d terminal, and the recording magnetic spatula The magnetic heads 31 to 34 are put into operation.

In this case, when the recording magnetic heads 31 and 32 scan the magnetic tape 54, the switch circuits 9 and 10 switch between the recording amplifiers 11 and 10. ．． Close to 13 side. However, the output signal of the recording equalization circuit 7 is sent to the switch circuit 9, the recording amplification ax 1.
The output signal of the recording equalization circuit 8 is supplied to the recording magnetic head 31 via the low retransformer 15 and the switch circuit 23, and the output signal of the recording equalization circuit 8 is supplied via the switch circuit 10, the recording amplifier 1, the low retransformer J7, and the switch circuit 25. When the recording magnetic heads 33 and 34 are supplied to the recording magnetic head 32 and written on the magnetic tape 54, the recording magnetic heads 33 and 34 run on the magnetic tape 54 IFf:? At last, switch circuit 9
．． 10 flashes on the recording amplifier 12.14 side.

As a result, the output signal of the recording equalization circuit 7 is transmitted to the switch circuit 9, the recording amplifier [2], and the near-crit transformer 16.

It is supplied to the recording magnetic head 33 via the switch circuit 24, and the output signal δ of the recording equalization circuit 8 (A switch circuit 109, recording amplifier 14, rotary transformer 18,
The signals are supplied to the recording magnetic head 34 via the switch circuit 26 and L7, and are recorded on the magnetic tape 54, respectively. The recording magnetic heads 31 to 34 are provided with recording equalization circuits 7 and 8.
The flow rubs the optimal record, and this results in 1. A good recording operation is performed.

Note that during recording, a control signal is supplied to the control head 58 by means not shown, and is recorded on the edge of the magnetic tape 54.

Next, the operation during playback will be explained.

In the rotating cylinder 53, a cylinder motor servo circuit 57 synchronizes the phase of the tack pulse from the tank head 59 with the frame pulse of a reproduced video signal, which will be described later.
A constant speed circuit is used so that one rotation is made for one frame of this video signal. The magnetic tape 54 is also controlled by a capstan motor servo circuit 56 so that a control signal reproduced from the magnetic tape 54 by a control head 58 and a tack pulse from a tack head 59 have a predetermined phase relationship. 55 is controlled to run at a constant speed.

When the reproducing magnetic heads 35 to 38 are normal, the switch circuits 27 to 3o close terminals a and b by the control signal supplied from the control 'II signal generator 60 to the d terminal, and the reproducing magnetic heads 35 to 38 are closed. 35 to 38 are activated.

In addition, the capstan motor servo circuit 56 and the cylinder motor servo circuit 57 are operated in accordance with control signals from the control signal generator 60 so that the reproducing magnetic heads 35 to 38 can correctly scan the tracks on the magnetic tape 54. ．． Determine the phase relationship that should be taken between the control pulse and the tack pulse in section F, and the phase relationship that should be taken between the tack pulse and the video signal to be reproduced.

The switch circuits 43 and 44 are controlled by a head 9 sliding signal formed from a tack pulse output by the tack head 59 in a cylinder motor servo circuit 57. As described above, when the reproducing magnetic heads 35 to 38 are normal, when the reproducing magnetic heads 35 and 36 scan the tracks on the magnetic tape 54, the switch circuits 43 and 44 are connected to the low cryotransmission 19 and 21 sides, respectively. Close to. The reproduction signal of the reproduction magnetic head 35 is transmitted through the switch circuit 27 and the preamplifier 3.
9. The reproduction signal of the reproduction magnetic head 36 is supplied to the reproduction equalization circuit 45 via the rotary transformer 19 and the switch circuit 43, and is reproduced etc. via the switch circuit 29, the preamplifier 41, the rotary transformer 21, and the switch circuit 44. is supplied to the conversion circuit 46. Next, the magnetic head for reproduction 37.38
When scanning the tracks on the magnetic tape 54, the switch circuits 43, 44 are closed to the low retransistor 20, 22 side. A reproduction signal from the reproduction magnetic head 37 is supplied to a reproduction equalization circuit 45 via a switch circuit 28, a preamplifier 40, a rotary transformer 20, and a switch circuit 43.
The reproduction signal of the magnetic head for reproduction on the third day is a switch circuit 38,
A reproduction equalization circuit 46 is supplied via a preamplifier 42, a rotary transformer 22, and a switch circuit 44.

As described above, the reproduction signals of the reproduction magnetic heads 35 and 37 are spliced together by the switch circuit 43 and supplied to the reproduction equalization circuit 45 as the reproduction signal of the negative channel. Furthermore, the reproduction signals of the reproduction magnetic heads 36 and 38 are also spliced together by the switch circuit 44 and supplied to the reproduction equalization circuit 46 as the reproduction signal of the other channel.

The reproduction equalization circuits 45 and 46 control the magnetic tape 54 and the reproduction magnetic head 3 according to control signals from the control signal generator 60.
The transmission characteristics (frequency characteristics) consisting of 5 to 38 are corrected to obtain optimum gain and phase characteristics for reproducing digital data. The output signals of the reproduction equalization circuits 45 and 46, which have been subjected to the correction processing in this way, are sent to the demodulation circuits 47 and 48, respectively.
demodulated into digital data, deshuffled and E
C, is supplied to C decoding circuits 49 and 50. These deshuffling/ECC decoding circuits 49 and 50 rearrange the digital data whose order at the time of recording was disorganized into the original order.1. Furthermore, data errors such as d: are corrected in the tape-to-rad transmission system using the error correction code added during recording. The two channels of digital data output from the deshuffling and ECC decoding circuits 49 and 50 are combined by the D/AI conversion and channel synthesis circuit 51 to become a digital video signal, which is further converted to the original analog video signal and sent to the output terminal 52. is output from.

As described above, when the reproduction magnetic heads 35 to 38 are normal, the reproduction equalization circuit 45.
46 to ensure good playback operation.

The above was a case where both the recording magnetic heads 31 to 34 and the reproducing magnetic heads 35 to 38 were normal, but the recording magnetic heads 31 to 34 or the reproducing magnetic heads 35 to 38
is abnormal, the control signal output from the control signal generator 60 changes, and the switch circuits 23 to 3 change accordingly.
The state of 0 changes. This will be explained with reference to FIG.

FIG. 3(a) shows that the recording magnetic heads 31 to 34 are normal during recording, or that the reproducing magnetic head 35 is normal during reproduction.
38 is normal (hereinafter referred to as P1 mode), the states of the switch circuits 23 to 30 are shown. In this P1 mode, the terminals a and b are closed, and in FIG. On 15.17 and 16.18, the reproducing magnetic heads 35, 36, 37.38 are connected to preamplifiers 39, 4 via switch circuits 27, 29, 28, and 30, respectively.
Connected to 1.40.42.

For example, even if the recording magnetic heads 31 to 34 are normal and the reproducing magnetic heads 35 to 38 are abnormal, the switch circuits 23 to 30 are in the P1 mode and the third
It is in the state shown in Figure (a). In the opposite case, switch times E, 23-30 are in P1 mode during playback.

FIG. 3(b) shows the states of the switch circuits 23 to 30 when the recording magnetic heads 31 to 34 are abnormal during recording (hereinafter referred to as P2 mode). In this P2 mode, the b and c terminals are The gap closes.

Now, assuming that at least one of the recording magnetic heads 31 to 34 is abnormal due to damage or wear, the switch circuits 23 to 30 are controlled by the control signal from the control signal generator 60 during recording. As P2 mode, c
The terminals are closed (FIG. 3(b)), so that the recording magnetic heads 31 to 34 are connected to the rotary transformers 15 to 18.
become inactive and are replaced by
N% head 7 for reproduction is switch circuit 2B, 23.0-
The reproducing magnetic head 35 is connected to the recording amplifier 11 via the cryotransformer 15, the recording amplifier 12 is connected via the rotary transformer 16, the reproducing magnetic head 38 is connected to the switch circuit 30°25, and the rotary transformer 1.
7 to the recording amplifier 13, and the reproducing magnetic head 36
are connected to the recording amplifier 14 via switch circuits 29 and 26 and the rotary transformer 18, respectively. Therefore, the recording signal of one channel outputted from the recording equalization circuit 7 is transferred to the recording signal of the other channel outputted from the recording equalization circuit 8 by the reproduction magnetic head 37.35 instead of the recording magnetic head 31.33. The recording signals of the channels are respectively recorded on the magnetic tape 54 by the reproducing magnetic heads 38 and 36 instead of the recording magnetic heads 32 and 34. At the same time, the recording equalization circuit 7.8 uses the control signal from the control signal generator 60 to determine the frequency characteristics of the recording current in the reproducing magnetic head 37.35 and the reproducing magnetic head 38.36. The equalization characteristics are switched so that the recording characteristics are optimized.Thereby, the reproducing magnetic heads 35 to 38 perform a recording operation while maintaining good recording characteristics.

FIG. 3(c) shows the states of the switch circuits 23 to 30 when the reproduction magnetic heads 35 to 38 are abnormal during reproduction (hereinafter referred to as P3 mode). In this P3 mode, the c and a terminals are The gap closes.

Now, if any one of the reproduction magnetic heads 35 to 38 is abnormal, during reproduction, the switch circuits 23 to 30 switch between the c and a terminals as P3 mode by the control signal from the control signal generator 60. close. As a result, the reproducing magnetic heads 35 to 38 are disconnected from the preamplifiers 39 to 42, respectively, and become inactive, and the recording magnetic heads 35 to 38 are replaced with
- The RAD 31 is connected to the preamplifier 40 via the switch circuits 23 and 28, the recording magnetic head 33 is connected to the preamplifier 39 via the switch circuits 24 and 27, and the recording magnetic head 32
is sent to the preamplifier 42 via the switch circuits 25 and 30,
Recording magnetic helads 34 are connected to preamplifiers 41 via switch circuits 26 and 29, respectively. Therefore, the recording magnetic head 31 replaces the reproducing magnetic heads 35 to 38.
.about.34 reproduce signals from the magnetic tape 54, and these reproduced signals are spliced by switch circuits 43 and 44 and supplied to reproduction equalization circuits 45 and 46. At the same time, the reproduction equalization circuits 45 and 46 control the recording magnetic heads 31 to 3 by the control signal from the control signal generator 60.
Equalization characteristics are set so that optimal gain and phase characteristics can be obtained for the reproduced signal from 4. This allows the recording magnetic heads 31 to 34 to perform a reproducing operation while maintaining good reproducing characteristics.

FIG. 4(a) is a circuit diagram showing the general configuration of the recording system from the recording amplifier to the magnetic head in FIG.
In the figure, a recording system including a recording amplifier 11, a rotary transformer 15, and a magnetic head 31 or 37 is shown as a representative, but the other recording systems are also similar.

Moreover, FIG. 4(b) is an equivalent circuit of FIG. 4(a).

In FIG. 4(a), the recording amplifier 11 includes a transistor 61, resistors 62 to 64, capacitors 65 and 66, and a constant voltage source 67, and performs constant current driving. This recording amplifier 11 receives an input signal Vin through a rotary transformer 15 to a recording magnetic head 31 (or a reproducing magnetic head 37).
).

The equivalent circuit of such a recording system is shown in FIG. 4(b), in which αVin (α is a constant) is the converted equivalent input signal of the input signal Vin in FIG. 4(a), R
3 is the resistance value of the resistor 62 in FIG. 4(a), and L
+ and C+ are equivalent inductance and equivalent capacitance, respectively, when looking from the rotary transformer 15 toward the magnetic head side in FIG. 4(a).

Now, if the required band required for the recording signal is O-f, then
In order for this recording signal to be recorded well, the frequency characteristics of the recording current must be sufficiently flat within the required band (0 to fo), as shown by characteristic 68 in Figure 5. be.

On the other hand, in the recording system of FIG. 4(a), the resonance frequency is 2gE2c,
It has a frequency characteristic expressed by ``°'' (1).Here, the equivalent inductance I4 is also equivalent to the inductance of the magnetic head.

When the recording magnetic head 31 is normal, it is connected to the rotary transformer 15 during recording.If the resonance frequency expressed by the above equation (1,) at this time is f, then as shown in FIG. Since the inductance of the recording magnetic head 31 is set small, this resonance frequency f
, becomes higher.

In this embodiment, the resonance frequency f2 is set higher than the limit frequency 10 of the required band of the recording signal, and as a result, as shown in Part 5, this resonant frequency f2 is set higher than the limit frequency 10 of the required band of the recording signal.
0 to fo), a sufficiently flat frequency characteristic 68 can be obtained.

By the way, in FIG. 4(a), the recording magnetic head 3
1 becomes abnormal, the reproducing magnetic head 37 is connected to the rotary transformer 15. The resonant frequency of the recording system expressed by the above equation (1) at this time is assumed to be f. As shown in FIG. 2, the inductance of the reproducing magnetic node 37 is set large so that good reproduction can be achieved.

For this reason, as shown as characteristic 69 in FIG. 5, the resonant frequency f becomes small and the required band (0-
・fo) The inner number is included, and the frequency characteristic is not flat within this required band.

Therefore, in the recording equalization circuit 7 (FIG. 1), when the recording magnetic head 31 is used for recording, the characteristic 7 shown in FIG.
0, a flat recording equivalent characteristic is set, but when the reproducing magnetic head 37 is used for recording, the recording equalization is raised on the high frequency side, as shown as characteristic 71 in FIG. Be able to switch to your characteristics. With this recording equalization characteristic, the characteristic 69 in FIG. 5 is corrected by emphasizing the high frequency side, and a sufficiently flat frequency characteristic is obtained within the required band (0 to ro) similar to the characteristic 68.

In the first explanation below, it is assumed that the resonant frequency f of the reproducing magnetic helad 37 is lower than the upper limit frequency of 1° of the required band, but the present invention is not limited to this. This resonant frequency “1”
is the upper limit frequency f. Even if the recording magnetic head 3 is higher than
1 to the reproducing magnetic head 37, the Ihara frequency of the recording system will necessarily become lower, and for this reason, the required band (O
・~fu) The frequency characteristic l within the range changes to a considerable extent and deteriorates. Even in such a case, the recording equalization circuit 7
By switching the zero equalization characteristic, the frequency characteristic is corrected to the optimum one.

Furthermore, although the explanation in section 2 was about the frequency characteristics of gain, it goes without saying that the frequency characteristics of phase should also be similarly corrected for optimization.

FIG. 6 is a circuit diagram showing the general configuration of the reproduction system from the magnetic head to the preamplifier in FIG. , and other playback systems as well.

In the figure, a magnetic head 35 or 33 connected to a preamplifier 39 isometrically composed of a signal source 72, a resistor 73, and an inductance 74.

Further, the preamplifier 39 includes an amplifier 76 having a feedback loop of a capacitor 77 and a resistor 79 and a feedback loop of a capacitor 78 and a resistor 80.

Capacitor 75 is a parasitic capacitance generated between magnetic head 35 or 33 and preamplifier 39.

In such a reproduction system, the frequency characteristics from the magnetic head 35 or 33 to the preamplifier 39 are determined by the resistance 79.80.
By performing optimal negative feedback damping at
The resonant frequency is determined by the value L2 of 2rc7'''.

It is flat up to the vicinity. So, now, the modulation method % formula %
), the required band in this case would be up to the frequency 2fN (however, f2 is the Nyquist frequency), and for this purpose, the resonant frequency expressed by equation (2) must be higher than the frequency 2fx. There is a need to.

During reproduction, when the reproduction magnetic head 35 is normal,
This reproducing magnetic head 35 is connected to a preamplifier 39. Let f be the resonance frequency expressed by equation (2) in the reproduction system at this time. In the reproducing magnetic head 35, as shown in FIG. 2, the value L2 of the inductance 74 is set to be large in order to increase the reproducing output. The inductance value L2 of the reproducing magnetic head 35 is set so that the resonance frequency f is slightly higher than the upper limit frequency 2fN of the required band.
Set. Even if the inductance value t is set in this way, a sufficiently large reproduction output can be obtained, and therefore, an optimal reproduction operation with a large reproduction output can be performed while ensuring good frequency characteristics for the required band.

By the way, the reproduction signal detected by the reproduction magnetic head 35,
That is, the frequency characteristic of the output signal of the signal source 72 in FIG. 6 depends on the t-magnetic conversion characteristic of the tape head system, and is represented by the two-dot chain line 83 shown in FIG. Reproduction equalization circuit 4
51.46 (Figure 1), the frequency characteristic 8 shown in Figure 8
The input playback signal of No. 3 is M as shown by the dashed line in FIG.
Optimal equalization characteristic of 2-variable modulation type 84 (roll-off 1.0
curve). In this case, the equalization characteristics of the regenerative equalization circuits 45 and 46 correspond to the portion indicated by the upper right diagonal line between the frequency characteristic surfaces vA83 and 84 in FIG. This results in an equalization characteristic 86 shown by the two-dot chain line in FIG.

In addition, the frequency characteristics of the reduction section in Fig. 8 are 83°84
The difference in is corrected by an integrator.

Returning to FIG. 6, when there is an abnormality in the reproducing magnetic head 35 during reproduction, the recording magnetic head 33 is connected to the preamplifier 39. The above formula (2) in the reproduction system at this time
Let f4 be the resonance frequency expressed by .

In this case, as explained in FIG. 2 and 7, in the recording magnetic head 33, the inductance value Lt is made sufficiently small, so the resonant frequency f4 is necessarily the same as the previous resonant frequency \lf.
z, and as shown by the solid line in FIG. 7, the frequency characteristic 82 of the recycled yarn is flat within the required band and there is no problem.

However, as explained in FIG. 2, the head gap of the recording magnetic head is wider than the head gap of the reproducing magnetic head, and for this reason, the frequency characteristics of the reproduced signal detected by the recording magnetic head 33 is the frequency characteristic 83 of the reproducing magnetic head 35, as shown by a broken line 85 in FIG.
The high frequency characteristics will deteriorate more than this. Here, assuming that the equalization characteristics of the reproduction equalization circuits 45 and 46 (Fig. 1) are constant, even in this case, the frequency characteristics of the reproduction signal by the recording magnetic head 33 are corrected by the equalization characteristic 8G of Fig. 9. Therefore, the optimum frequency characteristic 84 shown in FIG. 8 cannot be obtained.

Therefore, when the recording magnetic head 35 performs reproduction, the equalization characteristics of the reproduction equalization circuits 45 and 46 correspond to the hatched area between the frequency characteristics 85 and 84 in FIG. , that is, it is switched as shown by the broken line 87 in FIG.

In this way, even if the reproducing magnetic head becomes abnormal,
Immediately, reproduction No. 18 can be obtained while ensuring optimum equalization characteristics with the recording magnetic head, and good digital data can be restored.

FIG. 10 is a block diagram showing a specific example of the reproduction equalization circuit 45 and 46 in FIG. 92 is a phase compensation circuit, 92 is an output terminal, 93 is an integrator, 94 to 97 are delay lines, 98 to 102 are coefficient units, and 103 is a mixer.

In the figure, the reproduced signal input from the input terminal 88 has its reduced frequency characteristic corrected by the integrator 93 (thereby, the frequency characteristic 83.8
5 and the frequency characteristic 84 is corrected), and is supplied to a transversal filter 90. The reproduced signal inputted to the transversal filter 90 is multiplied by the coefficient multiplier 98 and sequentially delayed by the delay lines 94.95, 96.97, and the outputs of these delay lines 94, 95, 96.97 are The signals are multiplied by 2, 3, 4, and 5 by coefficient multipliers 99, 100, 101, and 102, respectively.

The output signals of these coefficient multipliers 98-102 are mixed in a mixer 103. The output signal of this mixer 103 has its phase characteristics corrected by a phase compensation circuit 91 and is output from an output terminal 92.

Here, in the transversal filter 90, the delay line 9
4 to 97, coefficient multipliers 98 to 102, and mixer 103 set the frequency characteristics of the gain. And the system? 3m
Depending on the control signal supplied from the signal generator 60 to the input terminal 89, a signal is sent to the coefficient unit 98 depending on whether the reproducing magnetic head is used during reproduction or the recording magnetic head is used.
As shown in FIG. 9, the optimum equalization characteristic 86.02 is switched to the coefficient 86.02.
87 is set.

Note that in the tape head system, in principle, phase distortion does not occur, so the phase compensation circuit 91 is not particularly required. It can be used to compensate for phase distortion that sometimes occurs.

FIG. 11 is a block diagram showing a specific example of the means for matching the magnetic head and preamplifier in FIG. 1. The preamplifiers 39 to 42 have magnetic heads 35 and 3 for reproduction, respectively.
7, 36, 38, but when the recording magnetic heads 33, 31, 34, 33 are connected to these preamplifiers 39 to 42, respectively, these are matched with the reproducing magnetic heads 35, 37, . Since the inductance and the like are different from 36 and 38, the matching may deviate, and in this case, the regeneration efficiency decreases.

Therefore, in FIG. 11, the preamplifier 30 will be explained. This preamplifier 39 is connected to the reproducing magnetic head 35.
During playback, if the playback magnetic head 35 is normal and used for playback,
A control signal input from the control signal generator 60 to the input terminal 1051 closes the switch circuits 107 and 108 to the X side, and the reproduced signal is directly supplied to the preamplifier 39.

Further, when the magnetic recording head 33 is used for reproduction with the reproducing magnetic heald 35 in operation, the switches 107 and 108 are closed to the Y side by the control signal. As a result,
The L lance 109 for matching is the recording magnetic head 3.
3 and the preamplifier 39, allowing good impedance matching between them.

In particular, when recording is performed using the recording magnetic heads 31 to 34, there are images on the magnetic tape 54 as shown in FIG.
Tracks Tr, Tz shown by solid lines.

1゛5. .
P3. . . . are recorded to realize a standard tape format.

On the other hand, due to the positional relationship between the recording magnetic heads 31 to 34 and the reproducing magnetic fields 35 to 38 on the rotating cylinder 53 shown in FIG. 1. Suppose that the reproduction magnetic head 35 starts scanning the magnetic tape 54 when it starts scanning the track Tt position and reaches the center of the track T at time t2. The scanning locus deviates from the track T by a distance M i + equal to the scanning amount of the magnetic tape 54 at time (111+).

Therefore, if any of the recording magnetic heads 31 to 34 becomes abnormal and the reproducing magnetic heads 35 to 38 are used for recording instead, the tracks formed by the reproducing magnetic heads 35 to 38 will be as shown in FIG. , tracks T+ and Tz formed when the recording magnetic heads 31 to 34 are used for recording.

T5. For ・・・・・・・・・T1 ' T I
Distance as shown by the dashed line as ' I T 1 ' + ・・・・・・・・・Therefore, these tracks 'r+,
The positional relationship between Tt, T3, . . . and the control signals P+, Pg, Ps, . . . is based on the track T1. Tz, Ts,...
...and control signals P+, Pm, Ps,...
......, and the standard recording tape format cannot be obtained.

Therefore, in this embodiment, as shown in FIG. 1, the capstan motor servo circuit 56 is controlled by the control signal from the control signal generator 60, and the position on the magnetic tape 54 of the control signal recorded by the control head 58 is controlled. , as shown in FIG. 12, P,, P,, P,,...
Each distance from...! , PI′, Pt
, Ps', ......... By this,
Track TI' +T! ' , 'r3...
...and control No. 4M P+, P2', P3
. . . matches the standard recording tape format.

In FIG. 1, the rotational phase of the rotary cylinder 53 is determined by a cylinder motor servo circuit 57 between the frame pulse of the video signal input to the input terminal 1 and the tack head 5.
The tack pulses from 9 and 9 are controlled to have a predetermined phase relationship, and as a result, the recording magnetic heads 31 to
13(a) when 34 is used for recording.
As shown in FIG. 2, one field of the video signal from one vertical blanking period to the next vertical blanking period is recorded on each track on the magnetic tape 54. On the other hand, when recording is performed with the reproducing magnetic fields 35 to 38 while the rotational phase of the rotary cylinder 53 is controlled as described above, the recording magnetic head 3 on the rotary cylinder 53
Due to the misalignment between the magnetic heads 1 to 34 and the magnetic heads 35 to 38 for reproduction, the magnetic tape 5 is
The scanning period No. 4 is shifted from the scanning period by the recording magnetic heads 31 to 34, and the vertical blanking period is not located at both ends of the track on the magnetic tape 54.

For this reason, here, the reproducing magnetic head 35 is moved to the magnetic tape 54 a time T later than the recording magnetic head 31.
(Therefore, the reproducing magnetic heads 36, 37, and 38 also start scanning the recording magnetic heads 32, 38, respectively.
33. Scanning of the magnetic tape 54 is started with a delay of time T from 34), the data memory of the shuffling/ECC link code circuits 3 and 4 is controlled by a control signal from the control signal generator 60, and the data memories of the shuffling/ECC link code circuits 3 and 4 are Ring/ECC
The output signals of the encode circuits 3 and 4 are transferred to the magnetic head 3 for recording.
1 to 34 are delayed by a time T from when they are used for recording. As a result, as shown in FIG. 13(b),
One field of video signals from one vertical blanking period to the next vertical blanking period is recorded on each track formed on the magnetic tape 54 by the reproducing magnetic heads 35 to 38.

Next, during reproduction, the capstan motor servo circuit 56 normally operates so that the reproduction magnetic heads 35 to 38 correctly track each track on the magnetic tape 54 according to the circular recording tape format. .

When the recording magnetic heads 31 to 34 are used for reproduction with such servo applied, the rotating cylinder 5
Due to the misalignment of the recording magnetic heads 31 to 34 and the reproducing magnetic heads 35 to 38 in 3-H, the recording magnetic head 31 corresponds to this misalignment, as shown by the broken line in FIG. Therefore, the trough T1 is scanned with a shift by that amount (the same applies to the other recording magnetic heads 32 to 34).

Therefore, in FIG. 1, the phase of the control signal from the control head 58 is changed in the capstan servo circuit 56 by the control signal from the control signal generator 60, and the running phase of the magnetic tape 54 and the rotation cylinder 53 are changed. For example, the recording magnetic heads 31 to 34 change the relationship with the rotational phase so that the recording magnetic head 31
As shown by solid lines 31 in the figure, each track of the magnetic tape 54 is scanned for reproduction in a correct tracking state.

At the same time, the switching timing of the switch circuits 43 and 44 is also changed. That is, the reproducing head switching signal for controlling these switch circuits 43 and 44 is formed by the cylinder motor servo circuit 57 based on the tack pulse from the tack head 59. Reproducing magnetic head 35
15 (a) is used for playback.
) With respect to the tack pulse shown in FIG. 15(b), a reproducing head switching signal is formed with the phase relationship shown in FIG. These magnetic heads are selected during the period in which the reproduction magnetic heads 37 and 38 scan the magnetic tape 54 for reproduction. On the other hand, when the recording magnetic heads 31 to 34 are used for reproduction, the recording magnetic heads 31, 32, 33, and 34 are activated by the time T4 earlier than the reproduction magnetic heads 35, 36, 37, and 38, respectively. Since scanning of the tape 54 is started, the switch circuits 43 and 44 move the reproduction magnetic head 35° to 36°.
The recording magnetic heads 31 and 32 are selected respectively at a time T4 earlier than the magnetic tape 54 starts to be scanned, and the reproducing magnetic heads 37 and 38 are set to scan the magnetic tape 54.
15(a) so that the recording magnetic heads 33 and 34 are respectively selected earlier than the start of scanning by a time T4.
The phase of the reproducing head switching signal is set as shown in FIG. 15(c) with respect to the tack pulse shown in FIG.

As described above, even if the reproducing magnetic heads 35 to 38 are used for recording instead of the recording magnetic heads 31 to 340, a track pattern conforming to the standard recording tape format can be obtained on the magnetic tape 54. In addition, recording magnetic heads 31 to 34 are used instead of reproducing magnetic heads 35 to 38.
Even if the magnetic tape 54 is used for reproduction, good reproduction from the magnetic tape 54 is possible.

In addition, in the above embodiment, the rotary transformers 15 to
18 is provided at the next stage of the recording amplifiers 11 to 14, and rotary transformers 19 to 22 are provided at the next stage to the preamplifiers 39 to 42, but these rotary transformers 15 to 22 may be located at different positions. .

Further, the control signal generator 60 may constantly monitor the recording t@2 preamplifier output, etc., and automatically detect an abnormality in the head from these, but the user can determine the abnormality and detect the abnormality. Control signal generator 60 controls input settings for abnormality instructions.
You may also do so.

Furthermore, in the above embodiment, if one of the recording magnetic heads 31 to 34 is abnormal at time 411, the reproducing magnetic heads 35 to 34 are replaced in place of these recording magnetic heads 31 to 34.
38, and also when reproducing magnetic heads 35 to 3 are used.
8, the recording magnetic heads 31 to 34 are used instead of the reproducing magnetic heads 35 to 38, but the present invention is not limited to this. If any of the recording magnetic heads 31 and 33 arranged at an angular interval of 180" is abnormal, the reproducing magnetic heads 35 and 37 arranged at the same angular interval of <180" are used in their place. You can also
The opposite may also be done.

This also applies to other recording magnetic heads and reproducing magnetic heads. In addition, instead of pairing the magnetic heads to be replaced in this way, it is possible to replace the abnormal reproducing magnetic head so that one corresponding reproducing magnetic head is used for recording instead of the abnormal recording magnetic head. Alternatively, one corresponding recording magnetic head may be used for reproduction. In the case of FIG. 1, the recording magnetic head 31
The reproducing magnetic head 35 corresponds to the reproducing magnetic head 35, and the recording magnetic heads 32, 33, and 34 correspond to the reproducing magnetic heads 36, 37, and 38, respectively.

〔Effect of the invention〕

As described above, according to the present invention, even if either the recording magnetic head or the reproducing magnetic head becomes abnormal, recording is performed using the other normal magnetic head.

Reproduction can be performed, and reliability can be greatly improved by immediately responding to abnormalities in the magnetic head.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a magnetic recording/reproducing device according to the present invention, FIG. 2 is a diagram showing the difference in characteristics between a recording magnetic head and a reproducing magnetic head, and FIG. 3 is a rotation diagram in FIG. 1. Figure 4(a) is a circuit diagram showing a specific example of the recording amplifier in Figure 1, and Figure 4(b) is its equivalent circuit diagram. , FIG. 5 is a frequency characteristic diagram of the recording current in FIG. 1, FIG. 6 is a circuit diagram showing an equivalent circuit of the reproducing magnetic head in FIG. 1 and a specific example of a preamplifier, and FIG. The frequency characteristic diagram of the circuit, Figure 8 is the electromagnetic conversion characteristic diagram of the tape head system in Figure 1, Figure 9 is the characteristic diagram of the reproduction equalization circuit in Figure 1, and Figure 10 is the reproduction etc. diagram in Figure 1. FIG. 11 is a block diagram showing an example of a matching means for the magnetic head and preamplifier in FIG. FIG. 13 is a schematic diagram showing the track pattern on the magnetic tape by each magnetic head.
FIG. 14 is a diagram showing the timing relationship between the magnetic head and the recorded signal during recording in FIG. 1, and FIG. FIG. 15 is a diagram showing the phase relationship between the tack signal and the reproducing head switching signal in FIG. 1. 1......Video signal input terminal, 2...
...A/D conversion/channel division circuit, 3, 4.
.......Shuffling/ECC encode circuit, 5.6...Modulation circuit, 7,8...
・・・・・・Recording equalization circuit, 9.10・・・・・・・・・
Switch circuit, 11-14... Recording amplifier, 15-22... Rotary transformer,
23-30...Switch circuit, 31-3
4......Magnetic head for recording, 35-38.
......Magnetic head for reproduction, 39-42...
・・・・・・Preamplifier, 43.44・・・・・・・・・
・Switch circuit, 45.46......Reproduction equalization circuit, 47.48...Demodulation circuit, 49
．． 50...Deshuffling/ECC decoding circuit, 51...D/A conversion/channel synthesis circuit, 52...Video signal output terminal , 53...Rotating cylinder, 54...
...... Magnetic tape, 55... Capstan motor, 56... Capstan motor servo circuit, 57... Cylinder motor servo circuit, 58... Control head, 59... Tack head, 60
......Control signal generator. Figure Self 4”J Figure Figure Figure Factor Frequency Figure Figure N Circular Wave Number Factor Figure 13 Figure 10 Figure 15

Claims (1)

[Claims] 1. A recording magnetic head and a reproducing magnetic head are provided separately, and an input information signal is processed by a recording processing means and recorded on a magnetic recording medium by the recording magnetic head, reproducing the information signal from the magnetic recording medium with the reproducing magnetic head;
In a magnetic recording and reproducing apparatus in which the reproduced information signal is processed by a reproduction processing means, the control signal generating means generates a control signal when the recording magnetic head is abnormal during recording; recording head selection means for selecting the reproducing magnetic head in place of the recording magnetic head as the recording head for the information signal from the recording processing means according to a signal; Provided is recording equalization means whose equalization characteristics are switched by
1. A magnetic recording and reproducing apparatus, characterized in that, when the recording magnetic head is abnormal, the reproducing magnetic head can record the information signal with a recording current having optimal frequency characteristics. 2. In claim 1, the information signal is a digitized video signal, the magnetic recording medium is a magnetic tape, and the recording magnetic head and the reproducing magnetic head are respectively provided at different positions on a rotating cylinder. The recording processing means is provided with means for switching the delay amount of the information signal according to the control signal, and means for switching the recording timing of the control signal recorded on the magnetic tape according to the control signal. 1. A magnetic recording and reproducing apparatus, characterized in that the track pattern on the magnetic tape is the same regardless of which of the recording magnetic head and the reproducing magnetic head is selected as a recording head. 3. A recording magnetic head and a reproducing magnetic head are provided separately, and the input information signal is processed by the recording processing means and recorded on the magnetic recording medium by the recording magnetic head, and the information signal is recorded from the magnetic recording medium. Reproducing the information signal with a reproducing magnetic head,
In a magnetic recording and reproducing apparatus in which the reproduced information signal is processed by a reproduction processing means, the control signal generating means generates a control signal when the reproduction magnetic head is abnormal during reproduction; reproducing head selection means for selecting the recording magnetic head in place of the reproducing magnetic head as a reproducing head for the information signal from the magnetic recording medium in response to a signal; a reproduction equalization means whose equalization characteristics are switched by
A magnetic recording/reproducing apparatus characterized in that the information signal can be reproduced by the recording magnetic head with optimum frequency characteristics when the reproducing magnetic head is abnormal. 4. In claim 3, the information signal is a digitized video signal, the magnetic recording medium is a magnetic tape, the digitized video signal and the control signal are recorded, and the recording magnetic head and the reproducing magnetic head are respectively provided at different positions on the rotating cylinder, and means for varying the timing of the control signal reproduced from the magnetic tape in response to the control signal; means for varying the timing of the reproducing head switching signal generated in synchronization with the rotational phase of the rotary cylinder, so that good tracking can be achieved regardless of whether the reproducing magnetic head or the recording magnetic head is selected as the reproducing head. A magnetic recording and reproducing device characterized in that the digitized video signal can be reproduced satisfactorily using information.