JPH08306001A - High speed reproducing video tape recorder - Google Patents

Abstract

PURPOSE: To provide a high speed reproducing video tape recorder capable of mutually evading the effect of a head resonance frequency at the time of normal reproduction and high speed reproduction and improving an S/N. CONSTITUTION: Rotary transformers RT1, RT2 capable of revising a step-up ratio according to the times at the time of high speed reproduction and normal reproduction are provided between reproducing heads PB1, PB2 and reproducing amplifier circuits 6, 7. At the time of high speed reproduction, switches SW2, SW3 are shifted to an output terminal 31 side, and secondary inductance are reduced, and parallel resonance frequencies decided by the inductance and the input capacitance of the amplifier circuits 6, 7 are increased. At the time of normal reproduction, the switches SW1, SW2 are shifted to the output terminal 30 side, and the secondary inductance are increased, and the parallel resonance frequencies decided by the inductance and the input capacitance are reduced. Thus, no parallel resonance frequency at the time of normal reproduction enters a high speed reproduction frequency band, and the S/N is improved, and further, at the time of normal reproduction, it need not reduce a reproducing level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder, and more particularly to a digital video tape recorder equipped with a transformer suitable for high speed reproduction by increasing the rotational speed of a drum.

[0002]

2. Description of the Related Art In recent years, analog video tape recorders have become widespread, but digital VTRs have been used as video tape recorders (hereinafter referred to as VTRs) in pursuit of high image quality.
Is proposed. A track pattern of a recording format proposed as a digital VTR, for example, a home digital VTR, has a track pattern as shown in FIG.

One track on the tape 1 consists of a video track 2, an audio track 3 and a tracking signal track 4, and 10 tracks up to a circle 10 convert one frame of image and sound into digital signals. It is recorded in the state where it was written. When the digital signal recorded from the tape 1 having the track pattern is reproduced, when the rotary drum 5 shown in FIG. 10 is rotated once, the reproduction heads PB1 and PB2 alternately reproduce one track at a time. Therefore, when the rotary drum 5 rotates 5 times, the reproducing heads PB1 and PB2 respectively reproduce 5 tracks, and thus reproduce a total of 10 tracks, that is, an image signal and an audio signal for one frame.

On the other hand, in the case of recording, the rotary drum 5 is rotated five times, and the recording heads REC1 and REC2 record 10 tracks, that is, an image signal, an audio signal and a tracking signal for one frame.

A digital VTR for recording and reproducing in this way
An example of the configuration will be described based on the block diagram shown in FIG. In the digital VTR of FIG. 6, the reproducing head P
The reproduction signals as shown in FIGS. 9A and 9B taken out from the track to circle 10 at B1 and PB2 are amplified by the reproduction amplifier circuits 6 and 7, and then the reproduction head P is reproduced.
Both signals reproduced by B1 and PB2 are switch means SW1.
In this way, a continuous reproduction signal for one frame as shown in FIG. 9C is obtained.

The reproduced signal for one frame is input to the A / D conversion circuit 8 which constitutes the waveform equalizer, and the code error of the reproduced digital signal is prevented from occurring. The A / D
The conversion circuit 8 is driven by the clock signal generated by the clock signal generation circuit 10 with the output signal of the PLL circuit 9 synchronized with the reproduction signal as a reference.

The output signal of the A / D conversion circuit 8 is subjected to predetermined signal processing such as decoding, error correction and data expansion in the reproduction signal processing circuit 11. After that, the output of the reproduction signal processing circuit 11 is output to the D / A conversion circuits 12, 13, 1
Video signal output terminal 1 converted to analog signal at 4
5 and audio signal output terminals 16 and 17 are output as analog signals.

Next, the recording side will be described. First, the analog video signal input from the analog video signal input terminal 18 and the analog audio signal input from the analog audio signal input terminals 19 and 20 are A / D
The conversion circuits 21, 22, and 23 convert the signals into digital signals, and the recording signal processing circuit 24 performs predetermined signal processing such as data compression, addition of error correction code, and encoding to convert the signals into predetermined recording signals. . After that, the output signal of the recording signal processing circuit 24 is amplified by the recording amplifier circuits 25 and 26, and recorded on the track to the circle 10 by the recording heads REC1 and REC2 in the pattern as shown in FIG.

Both reproduction and recording by the digital VTR are configured to operate in the same time advance as a television signal (hereinafter referred to as 1 × speed). Therefore, as shown in FIG. 7, two digital VTRs 27, 2
When dubbing from one tape to another using the No. 8 tape, it is also performed at 1 × speed. As a result, a tape-to-tape editing operation or a tape duplication operation requires the same time as the reproduction time of the material to be dubbed, and these operations require a lot of time and labor.

Therefore, as a countermeasure against this, it has been proposed to increase the speed of the drum by doubling the number of rotations of the drum as compared with that during normal reproduction (1 × speed) and at the same time doubling the tape speed. That is, since one frame (10 tracks) in FIG. 8 is reproduced in a time of 0.5 frame, the working time is cut in half. The recording time can be cut in half by doubling the drum rotation speed and tape speed during recording as well as during reproduction.

However, the problem here is that the relative speed of the tape head in the double speed reproduction is twice that in the normal reproduction, so that as shown in FIG. The reproduction level of the double speed reproduction signal is doubled compared to the reproduction signal, but the reproduction signal frequency band and noise distribution are doubled. That is, assuming that the reproduction signal frequency f1 in the normal reproduction is 2, the reproduction signal frequency in the double speed reproduction is doubled to 2f1.

By the way, as shown in FIG. 11, the secondary side (stator coil side) of the rotary transformers RT1 and RT2.
Inductance L as seen from the rotary transformer RT1 side
₀ and the parallel resonance frequency f of the input portion of the reproduction equalizer amplifier circuit by the input capacitance C ₀ of the reproduction equalizer amplifier circuits 6 and 7
_{There is 01} = 1 / 2π√ (L ₀ · C ₀ ), and in order to prevent this parallel resonance frequency from entering the reproduction signal frequency band, the parallel resonance frequency is as shown in (A) of FIG. The frequency must be set to be slightly higher than the reproduction signal frequency band during normal reproduction (1 × speed reproduction). In FIG. 11, the AD conversion circuits 8 and P
The LL circuit 9, the clock signal generation circuit 10, and the reproduction signal processing circuit are collectively shown as a reproduction system digital signal processing circuit 29.

On the other hand, the inductance of the secondary side (stator coil) of the rotary transformers RT1 and RT2 between the reproduction heads PB1 and PB2 and the reproduction equalizer amplifier circuits 6 and 7 is set to a large value to set the rotary transformers RT1 and R2.
Conventionally, the S / N ratio has been improved by increasing the step-up ratio of T2 as much as possible and increasing the input level to the reproduction equalizer amplifier circuits 6 and 7. for that reason,
The reproduction signal frequency band is lowered to an allowable limit, for example, the reproduction signal frequency band is set to 20 MHz, the parallel resonance frequency f ₀₁ is set to, for example, 25 MHz, and the parallel resonance frequency f ₀₁ falls within the reproduction signal frequency band. I was trying not to.

However, as described above, the parallel resonance frequency f ₀₁
When 2x speed reproduction is performed by setting, the parallel resonance frequency f ₀₁ is included in the 2x speed reproduction signal frequency band as shown in FIG. Occurs and the error rate is significantly deteriorated.

Therefore, in order to prevent the parallel resonance frequency during normal reproduction from falling within the double speed reproduction signal frequency band, the step-up ratio of the rotary transformers RT1 and RT2 is decreased to decrease the inductance value on the secondary side. Therefore, if the parallel resonance frequency is increased to the parallel resonance frequency f ₀₂ that does not fall within the double speed reproduction signal frequency band, the input level of the reproduction equalizer amplifier circuits 6 and 7 at the time of normal reproduction becomes low, This causes S / N deterioration.

[0016]

In view of the above-mentioned problems, the present invention avoids the effects of the parallel resonance frequency during normal reproduction and high-speed reproduction, and improves the S / N ratio of the high-speed reproduction video tape recorder. Is in the point of providing.

[0017]

The high-speed playback video tape recorder of the present invention is provided with a transformer capable of changing the step-up ratio according to the frequency band of the playback signal between the playback head and the playback amplifier circuit. As an example, the winding on the side to which the reproduction amplification circuit of this transformer is connected is composed of three terminals, the winding start terminal of the winding is connected to one input terminal of the reproduction amplification circuit, and the other winding is connected. The two terminals are switched according to the frequency band of the reproduction signal and connected to the other input terminal of the reproduction amplifier circuit. In addition, as another configuration, a reproduction head, a rotary transformer, a reproduction amplification circuit, and an RF transformer provided between the rotary transformer and the reproduction amplification circuit are provided, and the RF is provided according to the frequency band of the reproduction signal. Change the step-up ratio of the transformer. As an example, the winding of the RF transformer to which the reproduction amplification circuit is connected is composed of three terminals, the winding start terminal of the winding is connected to one input terminal of the reproduction amplification circuit, and the other winding is connected. Are switched according to the frequency band of the reproduction signal and are connected to the other input terminal of the reproduction amplifier circuit.

[0018]

FIG. 1 shows a block diagram of a first embodiment of the present invention. In this embodiment, the arrangement of the heads on the rotary drum is the same as the conventional arrangement of the rotary drum 5 shown in FIG. In the block diagram of FIG. 1, the reproducing heads PB1 and PB2 are respectively connected to the primary side (rotor side) of the rotary transformers RT1 and RT2 whose step-up ratio can be changed.

On the secondary side of the rotary transformers RT1 and RT2, an output terminal 3 capable of changing the step-up ratio is provided.
0, an output terminal 31, and a common output terminal 32 are provided. The rotary transformers RT1 and RT2 are configured such that the winding ratio of the output terminal 30 is larger than that of the output terminal 31. In this case, the output terminal 31 is taken out from the center tap of the secondary winding, the output terminal 30 is taken out from the winding end of the secondary winding, and the common output terminal 32 is taken out from the winding start of the secondary winding.

Of the output terminals 30 to 32, the common output terminal 32 is directly connected to the non-inverting input terminals of the reproduction equalizer amplifier circuits 6 and 7, and the output terminals 30 and 31 pass through the switch means SW2 and SW3 and the reproduction equalizer amplifier circuit. 6, 7
Are switched and connected to the inverting input terminals of.

The switching means SW2 and SW3 are switched by a reproduction speed switching signal input from the reproduction speed switching signal input terminal 33, and the output terminal 3 is used during normal reproduction.
It is set so that the inverting input terminals of the reproduction equalizer amplifier circuits 6 and 7 are connected to the output terminal 31 side on the 0 side during double speed reproduction. Also, the reproduction equalizer amplifier circuit 6,
On the output side of 7, there is provided a reproducing system digital signal processing circuit 29 via a switch means SW1 for switching the outputs of the reproducing heads PB1 and PB2, and this point does not change the conventional configuration.

The operation of the block structure will be described below. The reproduced digital signals obtained by scanning the tape 1 (FIG. 8) with the reproducing heads PB1 and PB2 are wound by the rotary transformers RT1 and RT2, respectively. After being stepped up to a voltage proportional to the ratio, the signals are amplified by the reproduction equalizer amplifier circuits 6 and 7, respectively, and a continuous reproduction signal (C in FIG. 9) is obtained by switching by the switch means SW1. Digital signal processing circuit 29
Then, a predetermined process is performed and it is output as a reproduction output.

At the time of normal reproduction, that is, at 1 × speed reproduction, the switch means SW2 and SW3 use the reproduction speed switching signal to output the rotary transformers RT1 and RT2.
The output terminal 30 is connected to the output terminals 30, 30 of the amplifier equalizer circuits 6 and 7, and the output terminal 30 is connected to the inverting input terminal side of the amplification equalizer circuits 6 and 7. The rotary transformer R
At T1 and RT2, the windings are formed so that the winding ratio of the output terminal 30 is larger than that of the output terminal 31, so in this case, the rotary transformer RT
The step-up of the reproduction signal at 1 and RT2 is sufficiently large.

As a result, the rotary transformers RT1, RT
The parallel resonance frequency f ₀₁ due to the secondary side inductance L _{0 of 2} and the capacitance C _{0 of the} reproduction equalizer amplifier circuits 6 and 7 is
As shown in FIG. 12, it can be set to a point that matches the reproduction frequency band at the 1 × speed reproduction. On the other hand, during double speed reproduction, the switch means SW2 and SW3 are used for the rotary transformers RT.
The winding ratios of the rotary transformers RT1 and RT2 are set to be smaller than those at the 1 × speed reproduction.

Here, the rotary transformers RT1 and R
The number of primary-side windings of T2 is m, the number of secondary-side windings of the winding having the output terminal 30 set at the time of 1 × speed reproduction is n1,
When the number of secondary windings of the winding having the output terminal 31 set at the time of double speed reproduction is n2, the winding ratios are m: n1 and m: n2, respectively.

When n1 / n2 = 1/2, the inductance L ₂ on the secondary side of the rotary transformers RT1 and RT2 is proportional to the square of the number of windings. Therefore, L ₂ = L ₁ × (n1 / n2) ² = L ₁ × (1/2) ² . Therefore, the parallel resonance frequency f ₀₁ at the 1 × speed reproduction and the parallel resonance frequency f ₀₂ at the 2 × speed reproduction are respectively f ₀₁ = 1 / 2π√ (L ₁ · C ₀ ) f ₀₂ = 1 / 2π√ (L ₂ .C ₀ ) = [1 / 2π√ (L ₁
.C ₀ )] × 2, and thus f ₀₂ = f ₀₁ × 2.

That is, the parallel resonance frequency f ₀₂ at the time of double speed reproduction in which the number of windings is reduced to ½ is twice the frequency of the parallel resonance frequency f ₀₁ at the time of single speed reproduction, and the frequency is shown in FIG. As shown in, it is possible to set the parallel resonance frequency f ₀₂ higher than the reproduction frequency band during double speed reproduction.

In FIG. 1, the rotary transformer RT1,
Switch means S for selecting the output terminals 30 and 31 of RT2
W2 and SW3 can be configured by, for example, the electronic switch circuit shown in FIG. In FIG. 5, the output terminals 30 of the secondary windings of the rotary transformers RT1 and RT2 are shown.
Is connected to the drain of an N-channel field effect transistor (hereinafter referred to as FET) Q2, and the output terminal 3 is also connected.
1 is connected to the drain of the FET Q4,
The sources of Q2 and Q4 are the reproduction equalizer amplifier circuit 6
It is connected to the inverting input terminal of (7).

The gate of the FET Q2 is a transistor Q.
1 and the gate of the FET Q4 is connected to the collector of the transistor Q3. Further, a power source + V _{B is provided} between the sources of the FETs Q2 and Q4 and the inverting input terminal of the reproduction equalizer amplifier circuit 6 (7).
Is supplied with a voltage of + V _B / 2 divided by the resistors R1 and R2. The resistors R4 and R6 are isolation resistors.

Furthermore, the through resistor R3 to the base of the transistor Q1, the reproduction speed switching signal from the reproduction speed switching signal input terminal 33 through the base of the transistor Q ₃ are resistors R5 and the inverter 34 is supplied. This switching signal is supplied from a system controller (not shown) incorporated in the digital VTR.

Now, the reproduction speed switching signal input terminal 33
When the 1 × speed reproduction selection signal is supplied from the device and the selection signal becomes low level, the transistor Q1 is turned off through the resistor R3. Therefore, the FET connected by the resistor R4
The gate and source of Q2 have the same potential, and the FET Q2 is turned on. At the same time, the output of the inverter 34 becomes high level, so that the transistor Q3 is turned on through the resistor R5. For this reason, the voltage applied to the gate of the FET Q4 drops to the ground potential and becomes a negative potential with respect to the source to which the voltage + V _B / 2 is applied, so that the FET Q4 is turned off.

Therefore, the rotary transformer RT1 (R
As for the output terminal on the secondary side of T2), the output terminal 30 having a large number of windings is connected to the inverting input terminal of the reproduction equalizer amplifier circuit 6 (7). As a result, the parallel resonance frequency becomes f ₀₁ .

On the other hand, a reproduction speed switching signal input terminal 33
When a double speed reproduction selection signal is supplied to the transistor and the selection signal becomes high level, the transistor Q1 is turned on and the FET is turned on.
Q2 is off. Further, since the output of the inverter 34 becomes low level, the transistor Q3 is turned off and the FE
TQ4 is turned on. In this case, the rotary transformer RT
The output terminal of 1 (RT2) is the output terminal 3 with a small number of windings.
1 is connected to the inverting input terminal of the reproduction equalizer amplifier circuit 6 (7). As a result, the parallel resonance frequency becomes f ₀₂ .

As described above, when the tape 1 (FIG. 8) is reproduced at 1 × speed with a small output level, the rotary transformer R is used.
The output levels of T1 and RT2 are sufficiently stepped up to be taken out, and the S / N can be increased. Also,
High output level from tape 1 and wide frequency band 2
During double speed reproduction, the inductance of the secondary side of the rotary transformer RT1 (RT2) can be reduced, and the parallel resonance frequency f
It is possible to raise ₀₂ . That is, it is possible to change the parallel resonance frequency to twice f ₀₁ .

Although an electronic switch circuit is used as the switch means SW2, SW3, depending on the tape format, the output level from the reproducing heads PB1, PB2 may be small, and the switching noise generated by the FETs Q2, Q4 may affect. Therefore, in this case, it is preferable to use a small electromagnetic relay in place of the electronic switch means for switching.

Next, the second embodiment will be described. Figure 2
The block diagram of the second embodiment is shown in FIG. In this second embodiment, the rotary transformers RT1 and RT2 are
Instead of switching the number of secondary windings according to the reproduction speed, RF transformers T1 and T2 are provided after the roller transformers RT1 and RT2 to reproduce the number of secondary windings of the RF transformers T1 and T2. The step-up ratio is changed by switching according to the speed.

In the block diagram of FIG. 2, the reproducing heads PB1 and PB2, the rotary transformers RT1 and RT are used.
2, reproduction equalizer amplifier circuits 6 and 7, switch means SW
2, SW3, and a reproduction system digital signal processing circuit 29. In the case of this embodiment, as described above, the RF transformer T is provided after the rotary transformers RT1 and RT2.
1, T2, and an output terminal 35 with a large number of windings, an output terminal 36 with a small number of windings, and a common output terminal 37 on the secondary side of the RF transformers T1, T2.
Similar to the first embodiment, the switching means SW2 and SW3 change the step-up ratio of the transformers T1 and T2 and the parallel resonance frequency.

The reproduced signal taken out from the tape from the reproducing heads PB1 and PB2 is a rotary transformer RT.
1 and RT2, and is guided to the outside of the rotating drum, and the RF transformers T1 and T in the subsequent stage are maintained with a fixed winding ratio.
By switching the step-up ratio at 1 × speed reproduction and 2 × speed reproduction at 2, it is possible to change the equivalent inductance seen from the head side and change the parallel resonance frequency according to the reproduction speed.

In the case of this embodiment, the rotary transformer RT
1. If RT1 and RT2 are small, it is not possible to take many windings for changing the step-up ratio, which is an especially effective embodiment.

Next, a third embodiment shown in FIG. 3 will be described. In contrast to the first and second embodiments, the number of windings on the secondary side of the rotary transformers RT1 and RT2 and the RF transformers T1 and T2 is switched by one of the terminals in this embodiment. The step-up ratio is switched by both terminals.

In FIG. 3, the rotary transformer RT1,
As RT2, two secondary sides 2 coupled to the primary winding
Use a rotary transformer with terminal windings. The rotary transformers RT1 and RT2 have two-terminal windings L _B and L _C on the secondary side, and the two-terminal winding L _B has output terminals b and b ′, and the two-terminal winding L _C has output terminals c and c '
It has each.

The output terminals b and c of the secondary windings L _B and L _C are switched and connected to the non-inverting input terminal of the reproduction equalizer amplifier circuit 6 (7) through the switch means SW2. On the other hand, the output terminals b ′ and c ′ of the secondary windings L _B and L _C are switch-connected to the inverting input terminal of the reproduction equalizer amplifier circuit 6 (7) through the switch means SW3.

During the 1 × speed reproduction, the switching means SW2 and SW3 are switched to the output terminals b and b ′, and during the 2 × speed reproduction, the output terminals c and c ′ are switched to the reproduction equalizer amplifier circuit 6 ( Supply the reproduction signal to 7). FIG. 3 shows an example in which the two-terminal winding is provided on the secondary side of the rotary transformer RT1 (RT2), but the two terminals are provided on the secondary side of the transformers T1 and T2 in the embodiment shown in FIG. You may implement by providing two windings.

In the embodiment shown in FIGS. 2 and 3, the reproducing speed can be switched by the electronic switch circuit shown in FIG. 5, as in the embodiment shown in FIG.

Next, a fourth embodiment shown in FIG. 4 will be described. In each of the embodiments shown in FIGS. 1 to 3, when the reproduction speed is switched, one output winding is not used and is idle. Therefore, in order to avoid such a state, the secondary side windings shown in FIG. 4 are switched in series and parallel to change the inductance value of the secondary side windings, and as a result, the parallel resonance frequency is changed.

FIG. 4 shows the rotary transformer RT1 (RT
Although the example in which the secondary winding is provided on the secondary side of 2) is shown, the transformer T in the embodiment shown in FIG.
It may be provided on the secondary side of T1 and T2.

In FIG. 4, the rotary transformer RT1
On the secondary side of (RT2), two 2-terminal secondary windings L _D and L _E are provided, and output terminals d-d 'and e-e' are provided, respectively. Switching means S is provided between the output terminals d and e.
W4 has a switch means S between the output terminals d'and e '.
W5 has a switching means S between the output terminals d'and e '.
W6 is provided for each.

1 from the reproduction speed switching signal input terminal 33
When a double speed reproduction selection signal is input, the switch means SW
4 and SW5 are turned off, and the switch means SW6 is turned on. Then, the secondary windings L _D and L _E are connected in series, the secondary inductor rises, and the parallel resonance frequency can be set to a low frequency.

On the other hand, a reproduction speed switching signal input terminal 33
When the double speed reproduction selection signal is input from the switch means, the switch means SW4 and SW5 are turned on and the switch means SW6 is turned off. Then, the secondary windings L _D and L _E are changed to parallel connection, and as a result, the secondary side inductance is reduced, and it becomes possible to set the parallel resonance frequency to a high value. In the case of this embodiment, an extra switch means must be provided as compared with each of the above embodiments, but this is an effective embodiment when the transfer rate during reproduction is low.

The case where the present invention is applied to the digital VTR has been described as the above embodiment, but the problem is that the analog VT is used.
It is also common to R, and the step-up changing means can be applied to the analog VTR as it is.

Further, in the above embodiment, the high speed reproduction is 2
Although the description has been given for the double speed reproduction, in the case of the triple speed reproduction or more, similarly, it is possible to use the rotary transformer or the RF transformer in common by changing the winding ratio of the rotary transformer or the RF transformer.

[0052]

When high-speed reproduction is performed by increasing the number of rotations of the drum, the S / N at the time of normal reproduction with a small reproduction output level is obtained.
The reproduction output level is large, but the reproduction frequency band is widened, and it is possible to achieve compatibility with high-speed reproduction in which the head resonance frequency (parallel resonance frequency) needs to be increased.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of a second embodiment of the present invention.

FIG. 3 is a block diagram of a third embodiment of the present invention.

FIG. 4 is a block diagram of a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing an example of a switch means used in the present invention.

FIG. 6 is a block diagram of a digital VTR.

FIG. 7 is a block configuration diagram when dubbing using a digital VTR.

FIG. 8 is a diagram showing a tape recording pattern of a digital VTR.

FIG. 9 is a diagram showing a reproduction output pattern of a digital VTR.

FIG. 10 is a diagram showing an arrangement of recording / reproducing heads of a digital VTR.

FIG. 11 is a diagram illustrating generation of a parallel resonance frequency between a rotary transformer and a reproduction amplifier circuit.

FIG. 12 is a diagram showing reproduction signal frequency characteristics during normal reproduction and during high-speed reproduction.

[Explanation of symbols]

 PB1 and PB2 reproducing heads RT1 and RT2 rotary transformers SW1 to SW6 switch means T1 and T2 RF transformers 6 and 7 reproducing equalizer amplifier circuits 30 and 35 high winding ratio output terminals 31 and 36 small winding ratio output terminals 32 and 37 Common output terminal

Claims (10)

[Claims] 1. A high-speed reproduction video tape recorder comprising a transformer capable of changing a step-up ratio according to a frequency band of a reproduction signal between a reproduction head and a reproduction amplifier circuit. 2. The high-speed playback video tape recorder according to claim 1, wherein the winding of the transformer on the side to which the playback amplification circuit is connected is composed of three terminals, and the winding start terminal of the winding is one of the playback amplification circuits. A high-speed playback video tape recorder, characterized in that it is connected to an input terminal, the other two terminals of the winding are switched according to the frequency band of a playback signal, and is connected to the other input terminal of the playback amplifier circuit. 3. The high-speed playback video tape recorder according to claim 2, wherein the winding on the side to which the playback amplification circuit of the transformer is connected is composed of three terminals provided with a center tap, and the winding start terminal of the winding is played back and amplified. The input terminal of the circuit is connected, the center tap is connected to the other input terminal of the reproduction amplification circuit during double speed reproduction, and the winding end terminal is the other input terminal of the reproduction amplification circuit during normal reproduction. A high-speed playback videotape recorder characterized by being connected to. 4. The high-speed playback video tape recorder according to claim 1, wherein the winding on the side to which the playback amplification circuit of the transformer is connected is provided with two 2-terminal windings having different numbers of windings, and during normal playback High-speed playback characterized by connecting a 2-terminal winding with a large number of windings to the input terminal of the reproduction amplification circuit, and connecting a 2-terminal winding with a small number of windings to the input terminal of the reproduction amplification circuit during high-speed reproduction Video tape recorder. 5. The high-speed playback video tape recorder according to claim 1, wherein the winding on the side to which the playback amplification circuit of the transformer is connected is provided with a plurality of two-terminal windings, and the plurality of two-terminal windings are provided during normal playback. A high-speed playback video tape recorder characterized by being connected in series and connected to the input terminal of the playback amplifier circuit, and at the time of high-speed playback, a plurality of two-terminal windings were connected in parallel and connected to the input terminal of the playback amplifier circuit. 6. The high speed playback video tape recorder according to claim 1, wherein the transformer is a rotary transformer. 7. A reproduction head, a rotary transformer, a reproduction amplification circuit, and a transformer provided between the rotary transformer and the reproduction amplification circuit, and a step-up of the transformer according to a frequency band of a reproduction signal. A high-speed playback videotape recorder characterized by changing the ratio. 8. The high-speed playback video tape recorder according to claim 7, wherein the winding on the side of the transformer to which the playback amplification circuit is connected is composed of three terminals, and the winding start terminal of the winding is one of the playback amplification circuits. A high-speed playback video tape recorder, characterized in that it is connected to an input terminal, the other two terminals of the winding are switched according to the frequency band of a playback signal, and is connected to the other input terminal of the playback amplifier circuit. 9. The high-speed playback video tape recorder according to claim 7, wherein the winding on the side to which the playback amplification circuit of the transformer is connected is composed of three terminals provided with a center tap, and the winding start terminal of the winding is played back and amplified. Connected to one input terminal of the circuit, the center tap is connected to the other input terminal of the reproduction amplification circuit during double speed reproduction, and the winding end terminal is connected to the other input terminal of the reproduction amplification circuit during normal reproduction. A high-speed playback video tape recorder characterized by being connected. 10. The high-speed playback video tape recorder according to claim 7, wherein the winding on the side to which the playback amplification circuit of the transformer is connected is provided with two two-terminal windings having different numbers of windings, and during normal playback High-speed playback characterized by connecting a 2-terminal winding with a large number of windings to the input terminal of the reproduction amplification circuit, and connecting a 2-terminal winding with a small number of windings to the input terminal of the reproduction amplification circuit during high-speed reproduction Video tape recorder.