JPS6243858A - Control device for running of rotary head type tape recorder - Google Patents

Abstract

PURPOSE:To apply servo control to a running speed of a tape at high speed running by switching the 1st servo control signal for constant speed control and the 2nd speed control signal for constant torque control depending on the presence of an envelope detection signal. CONSTITUTION:The 1st servo control signal for constant speed control is formed by the 1st servo control signal generation section 13 based on an envelope detection signal of a high frequency signal in a reproducing signal on a magnetic tape at high speed running and the 2nd servo control signal for constant torque control is formed by the 2nd servo control signal generating section 23 based on an output signal of a bridge circuit 23a using a winding side reel motor 22 as a detection side, the 1st and 2nd servo control signals are fed alternatively to a motor drive section by the operation of a servo control signal selection output means based on a discrimination signal of a discrimination section 18 to apply servo control to the torque of the motor 22. Thus, the servo control is applied to the running of the tape with simple and low cost constitution and excellent high speed reproduction is made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a rotation system for controlling the running of a tape during high-speed running in a rotating head type tape recorder such as a rotating head type digital audio tape recorder or an 8 mm video tape recorder. The present invention relates to a travel control device for a head type tape recorder.

[Conventional technology]

Conventional rotating head type digital audio tape player: ]-
This kind of rotary head type tape recorder (hereinafter referred to as R-1 AT) and 8 mm high-speed tape recorder (hereinafter referred to as 8 mm VTR) has two rotary heads with different azimuth angles installed in a rotary cylinder. At the same time, a PCM signal of information in a constant frequency band, such as an audio signal, is recorded in the PCM area of each track of the magnetic tape that is helically scanned by both rotary heads. Note that a pilot signal for tracking control is also recorded on each track.

During playback, the tape is normally played back by normal playback with the tape running speed set to the standard speed, i.e. the same speed as during recording. At this time, since the tape runs at the standard speed, both heads are The tape is played back alternately along the track, and the running speed of the tape is servo-controlled to the standard speed based on the pilot signal for tracking control recorded on each track, so that stable playback is performed.

By the way, when adding a high-speed playback function such as a high-speed search function to this type of rotary head type cheap play, it is necessary to set the tape running speed IW higher than the standard speed to perform high-speed playback. 1) In the case of "Ai", for example, 1zo [] Grano Banshi J° High-speed after-reflection coating invention (PROPO8AL OFPROGRAM) published by Sony Corporation on February 2611, 1985.
NtJMBEIgu QIJICK A
FTERRECORDING: As described in 31, the tape running speed during high-speed playback is set to 20% of the standard speed.
It is considered to set the magnification to 0 to 300 times.

During high-speed playback, the running speed of the tape and the rotational speed of both heads are faster than during normal playback, so both heads alternately play the tape across several tracks diagonally, and the speed of the tape is increased based on the pilot signal. Servo control is no longer possible, and at this time the tape runs according to the rotation of the take-up reel motor, as in the case of rewinding, fast forwarding, etc.

[Problem that the invention seeks to solve]

By the way, the take-up reel motor is normally rotated by a constant level of driving power, and in this case, the reel motor is used for rewinding.

The running of the tape changes as fast forwarding progresses.

Therefore, if the tape is run in accordance with the rotation of the take-up reel motor during high-speed playback, the tape will no longer run at a constant speed and good playback will not be possible.

Therefore, during high-speed playback, the running of the tape must be servo-controlled by some method that does not use pilot signals, but R-DAT, 8 E! In rotary head type tape recorders such as JVTRs, no method has been invented for servo-controlling the running speed of the tape during high-speed playback.

Note that it is desirable to servo control the running of the tape in order to ensure stable operation not only during high-speed playback but also during rewinding and fast forwarding.

On the other hand, in a conventional audio tape recorder that uses a fixed audio head to record and reproduce analog audio signals on a magnetic tape, when running the tape at high speed during high-speed playback, for example, As described in the publication, the rotation period of the reel motor on the tape supply side and the rotation period of the reel motor on the take-up side are measured, and a certain weight is given to the larger or smaller of the measured circumferential rotation periods. The rotation of the reel motor on the take-up side is servo-controlled and the running of the tape is servo-controlled so that the sum of the weighted rotation period and the unweighted rotation period is always constant. ing.

Therefore, during high-speed playback, rewinding, and fast forwarding of rotary head tape recorders such as R-DAT and 8ES VTR,
That is, when the tape runs at high speed, it is conceivable to servo control the running of the tape by applying the method described in the above-mentioned publication. It is conceivable that the tape running control circuit be configured in blocks as shown in FIG.

To explain the operation shown in FIG. 7, the rotation of the tape supply reel motor (1) and take-up reel motor (2) is as follows.
Both reel motors t11, [2+ supply side detector 1' consisting of a magnetic plate and a Hall element attached to each
, ll are respectively detected by the winding side detector (4), and the detection signals of both detectors +31 and +4+ are manually inputted to the micro XI monitor (5), and the computer'I tTh) li, both detectors +31, +4) Both reel motors fl based on the count of each detection signal
), +21 rotation period and arithmetic processing such as weighting are performed tentatively to output a digital signal for servo control of the reel motor (2).

Furthermore, the tental signal for servo control of the reel motor (?) output from the computer +b+ is converted into analog by the analog converter (1)), and is transmitted from the converter (6) to the drive amplifier (7) to the reel motor (?). 2), analog drive power based on the tental signal is supplied.

Then, based on the drive signal, the reel motor (2) is servo-controlled so that the sum of the weighted rotation period and the unweighted rotation period is always constant, and thereby the tape runs without using a pilot signal. It becomes possible to servo control the speed to an optimal constant speed when driving at high speeds.

However, in the case of Fig. 7, the reel motor tl), +
To detect the rotation period of 2+, the detector +31, +
4+ etc. must be provided in the mechanical section, and the computer (5) must perform complicated arithmetic processing, resulting in problems of complexity and increased cost.

Furthermore, in the method disclosed in the above publication, it is necessary to set the maximum winding radius of the tape in the computer (5) in advance, and when using many types of magnetic tapes (including cassette tapes) with different lengths and thicknesses, requires preprocessing such as calculating the maximum winding radius of the tape each time it is run at high speed.In fact, many types of cassette tapes are used in R-DAT and 8mm VTR, so for example, Unless a maximum winding radius indicator is provided on the cassette half of each cassette tape, the pre-processing described above must be performed, and rapid high-speed playback, rewinding, and fast forwarding will not be possible, and the problem will become even more complicated. be.

And this invention applies to R-I) AT and 8mm VT.
Servo-controls the tape running speed regardless of the type of tape with a simple and inexpensive configuration without performing complex calculation processing when the tape is running at high speed, such as during high-speed playback of a rotary head type cheap recorder such as R. This is a technical issue.

[Means for solving problems]

This invention has been made in response to the above points, and includes a rotating head provided on a rotating cylinder, and a helical scan is performed by the head during normal running, and a high frequency signal of information in a certain frequency band is sent to each track. A rotary head type tape recorder is provided with a rotary head type tape recorder comprising a magnetic tape on which is recorded, the tape is run by the rotation of a take-up reel motor during high speed running, and the rotating head type tape is provided to control the running of the tape during high speed running. A travel control device for a recorder includes a travel mechanism that causes the #J tape to be wound around the cylinder and travels during high-speed travel, a reproduction control means that controls the head to reproduce, and envelope detection of the reproduction signal of the head. an envelope detection section, a first servo control signal forming section that forms a first servo control signal for constant speed control proportional to the frequency of the envelope detection signal of the high frequency signal output from the detection section, and the motor. a second servo control signal for constant rotation control proportional to the output signal of the bridge circuit;
a servo control signal forming unit; a determining unit that determines the presence or absence of an envelope detection signal of the high frequency signal and outputs a determination signal; A first servo control signal is output, and the second servo control signal is
A rotary head type tape recorder comprising: servo control signal selection output means for outputting a servo control signal; and a motor drive section for supplying motor drive power to the motor at the level of the output signal of the output means. It is a travel control device.

[Effect]

During high-speed running, such as during high-speed playback, the tape wraps around a rotating cylinder and the rotating head is controlled for playback, so the rotating head traverses the tape diagonally and plays back, and at this time, the IS of the rotating head is generated. The frequency of the envelope detection signal of the high frequency signal of information included in the signal changes in proportion to the running speed of the tape.

Further, a first servo control signal for constant speed control is formed based on the detection signal, and the drive power of the take-up reel motor is servo-controlled by the first servo control signal during a fixed period of the detection signal, and the drive power of the take-up reel motor is servo-controlled. A second servo control signal for constant rotation control is formed from the output signal of the bridge circuit having the detection side, and the drive power of the motor is servo-controlled by the second servo control signal during no period of the detection signal. When driving at high speed, the first The rotation of the motor is servo-controlled by the second servo control signal so that the tape running speed is always the constant speed based on the first servo control signal, and thereby the tape running is servo-controlled.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 to 6 showing one embodiment thereof.

Figure 1 shows a 2-head calski A/N system R-DAT.
The configuration when applied to is shown in the same figure) 3 and (8)
(9) is an envelope detection unit connected to the input terminal (8),
(10) is the frequency/voltage conversion circuit connected to the detection section (9), (11) is the conversion circuit tl (sample hold circuit connected to li, and (12) is the inverting input terminal ←) is the sample bold circuit ( 11) A differential amplifier connected to (
13) is a first servo control signal forming section consisting of a frequency/voltage conversion circuit t101, a sample hold circuit (II), and an amplifier (13).

(14) is a head switching pulse signal input terminal to which a head switching pulse signal is input, (15) is a running direction signal input terminal to which a tape running direction signal is manually input, and (+a) is a head switching pulse signal and running direction signal. This is a gate pulse generation circuit into which
) and outputs a gate pulse to the discrimination circuit described below. (
Reference numeral 1 denotes a reference signal generation circuit in which a running direction signal is manually input, and outputs a reference signal for stopping control, which varies depending on the tape running direction, to a non-inverting input terminal (1) of an amplifier (12).

(18) is a determination unit connected to the detection unit (9), which determines whether the envelope detection signal is the envelope detection signal of the PCM signal of the tape, and determines whether or not the envelope detection signal is the envelope detection signal of the PCM signal. , outputs a no-determination signal. (19) is a changeover switch forming servo discrimination signal selection output means, one contact (a) is connected to the output terminal of the amplifier (12), and one contact (a) is connected to the output terminal of the amplifier (12) by the discrimination signal of the discrimination section (18). ) and the other contact (1)).

C1)) is a phase compensation circuit connected to the switching piece of the switch (19), and (2I) is a motor drive amplifier connected to the compensation circuit (20), forming a motor drive section. (2
Reference numeral 21 is a take-up reel motor whose positive terminal is connected to an amplifier (21), and whose negative terminal is grounded via a second servo control signal forming section to be described later. (23) is a second servo control signal forming unit, which has a bridge circuit (to be described later) in which the motor (4) is the detection side, and forms a second servo control signal for constant rotation control proportional to the output signal of the bridge circuit. output to the other contact (b) of the switch (19).

The second servo control signal forming section (%) is configured as shown in FIG. 2, in which (23a) is the motor (
As shown in the figure, it is a bridge circuit in which the detection side is formed, and the remaining three sides are formed by resistors (R1), (R2), and (R3), respectively, and the negative terminal of the motor (22) and the resistor (R3).
A voltage proportional to the change in the internal resistance of the motor (as shown in the figure) is generated between the connection point α between the resistors (R1) and (R2) and the connection point β between the resistors (R1) and (R2). It is a differential amplifier connected to α, and its non-inverting input terminal (G) is connected to connection point β, and a signal proportional to the voltage between both connection points α and β, that is, an output signal of the bridge circuit (23a). Outputs a proportional signal. (23C') is a DC amplifier whose inverting input terminal (to) is connected to the output terminal of the amplifier (23b), and the non-inverting input terminal (g) is connected to the reference terminal (230's constant rotation A reference signal for control is input manually, and a second servo control signal is output to the contact (1) of the switch (19).

By the way, the tape is based on the R-1) AT format, in which pilot signals are recorded in the tracking areas at both ends of each track, and a relatively long PCM area is provided between the two tracking areas, and a constant frequency is set in the PCM area. PC that forms high frequency signals of band information
M signal is recorded, and I) CM double signal band is approximately 1 to 4.
It is set to 7MHz.

Further, the pair of rotating heads are provided at opposite positions of the rotating cylinder, and their azimuth angles are set to opposite positive and negative azimuth angles.

During recording, the tape is recorded by helical scanning of both heads, so the magnetic tape (T) has a third
As shown in the figure, a track recorded at a positive azimuth angle (
Tatra'y (tb
) are formed diagonally and alternately in the running direction. In addition,
■ and O in the figure indicate positive and negative azimuth angles.

Furthermore, during normal playback, the traveling mechanism is controlled so that the
(T) is wrapped around a rotating cylinder at a semi-velocity and is traced by a head with a positive azimuth angle, while the track (tb) is traced by a head with a negative azimuth angle, and the head trajectories of both heads are the solid lines in Figure 3. As shown in IIx, the trajectory follows each track (ta) and (tb).

On the other hand, during high-speed playback, rewinding, fast forwarding, etc., the tape (1゛) is controlled by the travel control mechanism.
is wound around a rotating cylinder and travels at 200 to 300 times the standard speed, the rotational speed of both heads is higher than that during normal reproduction, and both heads are controlled for reproduction by the reproduction control means.

Note that since the tape (T) is run by the rotation of the motor (two forces), the running speed of the tape ("I") is proportional to the rotational speed of the motor.

Since the tape (T) runs at high speed, the head trajectories of both heads diagonally cross several tracks (ta) and (tb) as shown by the solid line IIy in Figure 3, and the head with a positive azimuth angle Not only the track (ta) but also the l-rack (tb) is traced, and since the azimuth angle of the track (city) is a negative unmass angle, the track (tb
), almost no reproduced signal can be obtained during tracing.

Similarly, the negative azimuth angle head 'b, +-rack (tb
) as well as the track (ta), and at this time, almost no reproduced signal is obtained while tracing the track (ta).

Therefore, during high-speed running, the reproduced signal input to the detection section (9) via the input terminal (8) has an amplitude undulation as shown in FIG. The envelope detection signal outputted from the detection section (9) to the conversion circuit (10) by the envelope detection of the detection section (9) is proportional to the waveform as shown in FIG. It becomes a waveform signal.

By the way, in the case of R-DAT, the frequency of the PCM signal is 1M.
Although it is higher than Hz, the frequency of the waviness is about several KH2.

There, the PCM area of each track (ta), (tb)? The frequency of the envelope detection signal based on the blind metamorphosis signal is
tape (G) without being affected by the M signal frequency.
It changes only in proportion to the running speed.

Therefore, if the rotation of the motor is controlled so that the frequency of the envelope detection signal based on the reproduction signal of the PCM area of each track (ta) and (tb) is constant, servo control of the running speed of the tape (T) can be performed. can be done.

On the other hand, if the tape (T) runs at a nearly constant speed during high-speed running, the PCM area of each track (ta), (tb)
The timing at which the head switching pulse signal is traced is a predetermined period after a predetermined period of time from the rising edge and falling edge of the head switching pulse signal of the input terminal (14) shown in FIG. 5(a).

In the case of R-DAT, the tape (T) is wound around a rotating cylinder at 90 degrees and travels, and both heads are installed at positions 180 degrees apart from each other on the head cylinder, and the level change of the head switching pulse signal is caused by rotation. Since each track (ta)t(tb) occurs every half revolution of the cylinder, each track (ta)t(tb) is approximately 90 minutes from the rise and fall of the head switching pulse signal.
The reproduced signal input to the input terminal (8) at this time is as shown in FIG. 5(+)), and the period Z in FIG. 5(b) corresponds to each track (ta).

(tb) shows the playback period of the PCM area.

Therefore, the conversion circuit (10) converts the frequency of the input envelope detection signal into a voltage, and converts the voltage signal proportional to the frequency of the waviness, that is, the voltage signal proportional to the running speed of the tape, to the sample and hold circuit (10). Output.

Further, the generating circuit (16) uses the head switching pulse signal of the input terminal (14) and the running direction signal of the input terminal (15) to generate the signal during the reproduction period Z of the PCM area as shown in FIG. 5(C). Outputs a continuous pulse for a certain period of time.

In addition, in R-DAT, in order to keep track reading linear speed constant during high-speed playback, it is necessary to vary the speed depending on the running direction of the tape (T). Therefore, depending on the running direction, the frequency of the envelope detection signal and the PCM The timing at which areas are traced is off.

Therefore, when traveling at high speed, for example, 200 times the standard speed, in order to improve the stability of control, the period of the clock pulse is set to 23 periods of the PCM signal when traveling in the fast forward direction, and when traveling in the rewinding direction At this time, the period of one gate pulse is set to 64 cycles of the PCM signal, and the output timing of the gate pulse is varied based on the traveling direction signal.

Then, the sample and hold circuit (11) samples and holds the voltage signal of the reproduction period Z of the PCM area based on the gate pulse, and the voltage signal output from the sample and hold circuit 1$ (II), that is, each track (ta) +
A voltage signal proportional to the frequency of the envelope detection signal of the PCM area of (tb) is connected to the inverting input terminal (-) of the amplifier (12).
is input.

In addition, as mentioned above, since the frequency of the envelope detection signal with respect to the running speed differs depending on the running direction of the tape (T), based on the running direction signal ('3) of the input terminal (15), the generation circuit (17) outputs the signal to the amplifier. Two types of reference signals for constant speed control, that is, reference signals for setting a reference speed during high-speed running, are alternatively output to the non-inverting input terminal (1) of (12).

Then, from the amplifier (12□1 to the switch (opening) contact (
In a), a first servo control signal consisting of the difference between the voltage signal of the sample and hold circuit (11) and the reference signal, that is, a first servo control signal that changes in proportion to the envelope detection signal of the PCM signal is output. .

As mentioned above, the tape (T) wraps around the co-rotating cylinder by 90°, so the head switching pulse signal of 90° (
Tape (') is used between 180° and 270° (360°).
(2)) is not traced, and the first servo control signal is not output from the amplifier (12) during this time.

Also, in the trace period other than the PCM area,
), the first servo control signal is no longer output.

Therefore, a discriminator (18) is provided, and the discriminator (18) discriminates whether or not there is an envelope detection signal of the PCM signal.

That is, the envelope detection signal outputted from the detection section (9) has a DC component corresponding to the frequency of the undulation, and the PCM
In the case of an envelope detection signal, the level of the DC component is relatively high, as shown in Figure 6 (a), and in other cases, the level of the DC component is extremely high, as shown in Figure 6 (1)). low.

Therefore, the discriminator (18) compares the threshold level Vs shown by the broken lines in FIGS. 6(a) and 6(b) with the level of the DC component of the input envelope detection signal, and
A high-level discrimination signal is output for a certain period of time when the envelope detection signal of the PCM signal becomes equal to or higher than threshold level Vs, and a low-level discrimination signal is output for no period of time when the envelope detection signal of the PCM signal becomes less than or equal to the threshold level Vs. Output.

Then, a switch (1!1
) is switched to the contact (a), and the switch (19) is switched to the contact (b) based on low level discrimination. Therefore, while the first servo control signal is output from the amplifier (12), the switch (19) ) is held at contact (a), and the amplifier (
The first servo control signal of 121 is input to the amplifier (21) via the switch (+91) and the phase compensation circuit (20), and the voltage proportional to the first servo control signal is output from the amplifier (21) to the motor (2). Drive power is supplied, and at this time, based on the first servo control signal, the voltage of the drive power applied to the motor (2) changes so as to control the rotation of the motor (motor t22) to a reference speed during high-speed running; tape ('r)
The traveling speed of the machine is servo-controlled to a constant speed.

Note that the phase compensation circuit (20) integrates and averages the input signal to prevent fluctuations in servo control.

By the way, when the value of the internal resistance of the motor (221) is defined as rx, the internal resistance value rx changes in proportion to a change in rotational speed based on a change in load.

On the other hand, the resistances (R1), (R2), (R3) +
17) The values rl, r2゜r3 are the internal resistance values rX' of the motor (4) when the motor rotates at the reference speed.
On the other hand, rl and r3-rX'J2 are set to values that are in equilibrium.

Therefore, when the motor (22) rotates at the reference speed, the voltage between the connection points (1!, 8) is 0,
The voltage between the connection points r and β changes in proportion to the rotational speed of the motor (221).

Then, a signal proportional to the voltage between the connection points α and β is transmitted to the amplifier (
231)) is output to the amplifier (23C), and the amplifier (
23c) to the contact (1)) of the switch Q:+), a second water control signal consisting of the difference between the reference signal for constant rotation and the output signal of the amplifier (23b), that is, the motor (2 A second servo control signal proportional to the rotational speed is output.

Therefore, if the switch (12) is switched to contact 0) while the low-level discrimination signal is output from the discrimination section (18), that is, without any period of the envelope detection signal of the PCM signal, then the second Servo control signal is switched [+!
11, Amplifier (21) via phase compensation circuit (2[)
The rotation of the two motors is servo-controlled to constant rotation at the reference speed by the second servo control signal.

The rotation number Ω is the rotation number expressed by the formula 0−=(1+r+yr2)Vf/Ke.

Therefore, the rotational speed of the motor (2 units) is always servo-controlled to the reference speed by the first and second servo control signals, and the running speed of the tape (T) is servo-controlled to be constant.

Therefore, the running of the tape (T) during high-speed running is controlled by the first servo control signal based on the reproduction signal of the tape (T).
With the second servo control signal based on the output signal of the bridge circuit with the motor (22) as the detection side, servo control is always performed, and stable high-speed reproduction, rewinding, and fast forwarding can be performed.

In addition, there is no need to install a detector to detect the rotation of the motor (? force) in the mechanical part, and there is no need for complicated arithmetic processing, so there is no need to use expensive and complicated arithmetic processing devices such as microcomputers. Servo control can be performed with a simple and inexpensive configuration.

Further, since the length, thickness, etc. of the tape (T) do not affect servo control, rapid high-speed running servo control can be performed on various magnetic tapes without preprocessing.

Furthermore, the number of cycles of the one-gate pulse is relatively long, and
The phase compensation circuit (20) causes the first. Since the second servo control signal is averaged and fluctuations in servo control are prevented, even if an erroneous conversion occurs in the conversion circuit (10), for example, servo control will not fluctuate and stable servo control can be performed. .

Although the embodiment described above is applied to an R-DAT, it is of course applicable to various rotary head tape recorders such as an 8mm VTR.

〔Effect of the invention〕

As described above, according to the running control device for a rotary head type cheap recorder of the present invention, when running at high speed, the magnetic tape (
Based on the envelope detection signal of the high frequency signal in the reproduced signal of 'r), the first servo control signal forming section (1) forms the first servo control signal for constant speed control, and also generates the first servo control signal for constant speed control. (Bridge circuit with 221 as the detection side (
Based on the output signal of the second servo control signal forming section (23a), a second servo control signal for constant rotation control is formed by the second servo control signal forming section (4), and the servo control signal selection output means based on the determination signal of the discriminating section (18). As a result of the operation, the first and second servo control signals are selectively supplied to the motor drive unit, and the rotation of the motor (2 motors) is servo controlled. With this configuration, the running of the tape (T) can be servo-controlled and good high-speed playback can be performed.

[Brief explanation of drawings]

1 to 6 show one embodiment of the travel control device for a rotary head type tape recorder according to the present invention, FIG. 1 is a block diagram, FIG. 2 is a detailed wiring diagram of a part of FIG. 1, Figure 3 is an explanatory diagram of the trace of the rotating head, Figure 4 (a), (
b), Figures 5(a) to (C) and Figure 6(a). (b) is a waveform diagram for explaining the operation of FIG. 1, and FIG. 7 is a block diagram of an improved version of the conventional travel control device for an audiotape recorder. (9) Envelope detection unit, (13) First servo control signal forming unit, (18) Discrimination unit, (19) Changeover switch (21) Motor drive amplifier, (24 Take-up side reel Motor, (231/second servo control signal forming section, (2
3a) Bridge circuit, (T) Magnetic tape.

Claims (1)

[Claims] (1) Equipped with a rotating head provided on a rotating cylinder, and a magnetic tape that is helically scanned by the head during normal running and on which a high frequency signal of information in a certain frequency band is recorded on each track, and is wound during high speed running. In a running control device for a rotating head type tape recorder, which is provided in a rotating head type tape recorder that runs the tape by rotation of a take-side reel motor, and controls the running of the tape during high speed running, a traveling mechanism that causes the head to travel while being wound around the cylinder; a reproduction control means that controls the head to reproduce; an envelope detection section that detects an envelope of a reproduction signal of the head; and the high-frequency signal output from the detection section. a first servo control signal forming section that forms a first servo control signal for constant speed control proportional to the frequency of the envelope detection signal of the motor; and a bridge circuit in which a detection side is formed by the motor, the bridge circuit a second servo control signal forming section that forms a second servo control signal for constant rotation control proportional to the output signal of the high frequency signal; and a discriminating section that determines the presence or absence of an envelope detection signal of the high frequency signal and outputs a discrimination signal. , switching according to the discrimination signal, outputting the first servo control signal during a certain period of the envelope detection signal of the high frequency signal, and outputting the second servo control signal during a non-period of the envelope detection signal of the high frequency signal. 1. A travel control device for a rotary head tape recorder, comprising: servo control signal selection output means; and a motor drive section that supplies motor drive power to the motor at the level of the output signal of the output means.