JP2622422B2 - Servo controller for recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo control device of a recording / reproducing apparatus which stabilizes traveling of a recording medium using a control signal reproduced from the recording medium.

2. Description of the Related Art In a helical scan type magnetic recording / reproducing apparatus (hereinafter referred to as VTR) using a recording medium as a magnetic tape, a video signal is formed in a longitudinal direction on a video track formed diagonally on the magnetic tape. Control signals are recorded in the control tracks, and when a video signal is reproduced from the magnetic tape, a phase difference between the control signal reproduced from the magnetic tape and a phase reference signal generated separately is detected. The running of the magnetic tape is stabilized by controlling the rotation phase of a capstan motor that drives the running of the magnetic tape in accordance with the phase difference. At the same time, the rotational phase of the rotary head that scans the video track on the magnetic tape is also controlled. By controlling this and the rotational phase control of the capstan motor, the rotary head can correctly reproduce and scan the video track. That is, tracking control is performed so that the best tracking state is obtained.

According to such tracking control, when reproducing a magnetic tape recorded on another VTR, the rotating head correctly reproduces and scans the video track so that the video signal is reproduced with the maximum amplitude. However, in practice, there is a variation in the arrangement of each head and expansion and contraction of the magnetic tape for each VTR, so that the rotating head may not be able to reproduce and scan the video track correctly.

By the way, when reproducing a magnetic tape recorded on another VTR, the best tracking state cannot be obtained as described above. In the rotation phase control of the capstan motor, the phase reference signal and the reproduction control This is because the best tracking state is obtained when the signal and the signal have a predetermined predetermined phase relationship. Therefore, paying attention to this point, the level of the reproduced video signal is detected, the phase of the reproduced control signal is adjusted according to the detected level, and the phase relationship between the phase reference signal and the reproduced control signal in the best tracking state is made variable. There has been proposed a technique for establishing a relationship such that a reproduced video signal can be obtained at the maximum level (for example, Japanese Patent Laid-Open No. 54-114114).

[Problems to be Solved by the Invention] By the way, in a VTR, a failure of a control signal recording processing circuit or the like or destruction of a control head may occur, so that a control signal may be lost or may not be recorded on a magnetic tape. is there. Some industrial VTRs and the like are provided with means that enable simultaneous reproduction and recording, and this enables the recording state of the video signal to be monitored. For the control signals recorded by the separate control head, the recording state is not monitored. For this reason, if the control signal cannot be recorded for the above-described reason, the control signal is lost on the magnetic tape for a long time, or the video signal is recorded without being recorded.

Therefore, in a VTR that performs tracking control using a control signal reproduced from a magnetic tape, if the control signal is lost or not recorded for a long time on the magnetic tape to be reproduced, the rotating head will not be able to control the video track. The tracking control is not performed, and good reproduction of the video signal cannot be performed.

In many cases, software (programs) recorded on magnetic tape is a valuable item that cannot be reproduced again, and the control signal is missing or not recorded on the magnetic tape on which such software is recorded. Therefore, it is a very serious problem that good reproduction of the software cannot be performed.

A first object of the present invention is to solve such a problem and to provide a servo control of a recording / reproducing apparatus in which a good tracking state can be always obtained even on a recording medium in which a control signal is lost or recorded for a long time. It is to provide a device.

A second object of the present invention is to provide a servo control apparatus of a recording / reproducing apparatus which can record a new control signal in a portion of the recording medium where the control signal is missing or unrecorded.

[Means for Solving the Problems] In order to achieve the first object, the present invention provides an arithmetic processing means for detecting the amplitude of a reproduced signal due to a rotating head and generating a control signal for increasing the amplitude. A control signal detecting means for detecting that the control signal is not reproduced from the recording medium for a long time, a capacitative device which operates in accordance with a detection output of the control signal detecting means, and which is operated in accordance with the control signal output from the arithmetic processing means. Speed control means for controlling the speed of the stun motor.

In order to achieve the second object, the present invention further provides control signal generating means for generating a control signal having a predetermined phase relationship with the rotation of the rotary head, and means for supplying the control signal to the control head. Is provided.

[Operation] When the control signal is not reproduced from the recording medium for a long time, the phase control of the capstan motor cannot be performed, and the best tracking state in which the scanning locus of the rotary head coincides with the recording track cannot be maintained. Decreases. In such a state, the arithmetic processing means outputs a control signal and operates the speed control means to change the rotation speed of the capstan motor. The arithmetic processing means monitors the change in the amplitude of the reproduction signal accompanying the change in the rotation speed of the capstan motor, and when the amplitude decreases, outputs a control signal to reduce the rotation speed of the capstan motor to the above value. Is changed in the opposite direction.

When the rotation speed of the capstan motor changes, the positional relationship between the scanning track of the rotating head and the recording track changes,
The scanning state of the rotating head can be brought to the best tracking state.

Further, when the control signal output from the control signal generating means is supplied to the control head by the means while the scanning trajectory of the rotary head is maintained in the best tracking state as described above, the control signal is transmitted to the recording medium. The normal recording format is restored even if the long-range control signal is missing or the recorded recording medium has no control signal recorded at all. You.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a servo control device of a recording / reproducing apparatus according to the present invention, wherein 1 is a magnetic tape, 2 and 3 are rotary heads, 4 is a drum motor, 5 is a capstan motor, 6 is a frequency generator, 7 is a frequency-voltage conversion circuit, 8 is an adder, 9 is a phase control circuit, 10 is a control head, 11 is a control signal detection circuit, 12 is a tack head, 13 is a phase control circuit, and 14 is a preamplifier. , 15 is a reproduction processing circuit, 16 is an output terminal, 17 is an arithmetic processing circuit, 18 is a reference oscillator, 19 is a reference signal generation circuit, 20 is a variable delay circuit,
21 is a speed command signal generation circuit.

In FIG. 1, on a magnetic tape 1, a video signal is recorded on an oblique video track, and a control signal is recorded on a longitudinal control track.
The magnetic tape 1 runs by the rotation of a capstan motor 5 and rotates by a drum motor 4.
A video signal is reproduced by alternately scanning the magnetic tape 1 in an oblique direction, and a control signal is reproduced by a fixed control head 10 scanning the magnetic tape.

Next, the operation of this embodiment when the control signals are sequentially reproduced from the magnetic tape 1 by the control head 10 will be described with reference to FIG. 2. FIG. 2 is a waveform diagram showing signals at various parts in FIG. 1. Signals corresponding to FIG. 1 are denoted by the same reference numerals.

When the capstan motor 5 is rotating, a signal (FG signal) having a frequency proportional to the rotation speed is generated by the frequency generator 6.
And is supplied to a frequency-voltage conversion circuit 7 to be converted into a voltage representing a deviation from a specified frequency corresponding to a specified rotation speed of the capstan motor 5 and supplied to an adder 8 as a speed control signal. . Further, based on the output of the reference oscillator 18, the reference signal generation circuit 19 generates a phase reference signal c ′ for controlling the rotation phase of the capstan motor 5 and the drum motor 4.
The phase reference signal c 'is generated by the variable delay circuit 20 in which the amount of delay is set in accordance with the output signal of the arithmetic processing circuit 17. Then, the control head is used as the phase reference signal c.
The signal is supplied to the phase control circuit 9 together with the control signal d reproduced from the magnetic tape 1 by the signal 10. In the phase control circuit 9, a phase control signal corresponding to the phase difference between the phase reference signal c and the reproduction control signal d is generated, and the adder 8 adds the generated phase control signal to the speed control signal from the frequency-voltage conversion circuit 7 to cancel. The power is supplied to the pusher motor 5.

In this way, the speed and phase of the capstan motor 5 are controlled, and the magnetic tape 1 runs at a predetermined speed and maintains a predetermined phase relationship between the phase reference signal c and the reproduction control signal d. I do.

The drum motor 4 is driven by a speed control mechanism (not shown).
It rotates at a predetermined speed. By the rotation of the drum motor 4, a tack signal b representing the rotational phase of the drum motor 4 is generated by the tack head 12, and is supplied to the phase control circuit 13 together with the phase reference signal a output from the reference signal generation circuit 19. In the phase control circuit 13, a phase control signal corresponding to the phase difference between the tack signal b and the phase reference signal a is generated, whereby the phase of the drum motor 4 is controlled.

The rotating heads 2 and 3 are rotated by the drum motor 4 whose speed and phase are controlled as described above, and the magnetic tape 1 is alternately reproduced and scanned, thereby reproducing a video signal. These rotating heads
The playback video signals from 2, 3 are sent to the preamplifier 14
Each is amplified and combined using a switching signal generated from the tack signal b to form a series of video signals.

A series of video signals output from the preamplifier 14 are, on the one hand, subjected to processing such as demodulation by a reproduction processing circuit 15 and then output to the outside from an output terminal 16, but on the other hand, comprise a microcomputer or the like. It is supplied to the arithmetic processing circuit 17.

The arithmetic processing circuit 17 amplitude-detects the supplied video signal, for example, a signal recorded and reproduced with a constant amplitude (hereinafter, referred to as a constant amplitude signal), such as a frequency-modulated luminance signal, and outputs the detected output. While monitoring the level, a control signal f corresponding to the change in the level is output. The delay amount of the variable delay circuit 20 changes according to the control signal f. The direction in which the amount of delay changes is the direction in which the amplitude of the constant amplitude signal reproduced by the rotating heads 2 and 3 is the maximum, that is, the direction in which the rotating heads 2 and 3 are in the best tracking state. Hereinafter, the operation of the arithmetic processing circuit 17 for this will be described in more detail.

The arithmetic processing circuit 17 outputs the control signal f while monitoring the detection level of the constant amplitude signal. Every time this control signal is output once, the delay amount of the variable delay circuit 20 increases or decreases by one step. Assuming that the change amount of the delay amount for one step is Δt, the arithmetic processing circuit 17 now sets the delay amount of the variable delay circuit 20 to Δ
When the phase is reduced by t, the phase of the phase reference signal c advances by Δt, and accordingly, the rotation phase of the capstan motor 5 advances, the running phase of the magnetic tape 1 advances, and the video track on the magnetic tape 1 advances. The positional relationship between the scanning trajectories of the rotary heads 2 and 3 changes. As a result, when the detection level of the constant amplitude signal detected by the arithmetic processing circuit 17 increases, the delay amount of the variable delay circuit 20 is changed so that the rotating heads 2 and 3 are in the best tracking state. Become
The arithmetic processing circuit 17 outputs the control signal f to output the variable delay circuit 20
The delay amount of the variable delay circuit 20 is sequentially reduced by Δt as long as the detection level of the constant amplitude signal increases. If the detection level of the constant amplitude signal is reduced when the delay amount of the variable delay circuit 20 is shortened by Δt, the deviation between the scanning track of the rotating heads 2 and 3 and the video track is increased. ,
The arithmetic processing circuit 17 then outputs a control signal f for increasing the delay amount of the variable delay circuit 20 by Δt.

As described above, the arithmetic processing circuit 17 changes the delay amount of the variable delay circuit 20 in a direction in which the rotating heads 2 and 3 are in the best tracking state, and when the detection level of the constant width signal becomes close to the maximum, The delay amount of the variable delay circuit 20 is alternately increased and decreased by Δt. As a result, the rotating heads 2 and 3 are kept in the best tracking state, and the detection level of the constant amplitude signal is slightly reduced by increasing and decreasing the delay amount by Δt as shown in FIG. Will only change to

Thus, when the control signal d is reproduced from the magnetic tape 1 by the control head 10, the amount of delay of the variable delay circuit 20 is controlled,
The scanning state of the rotating heads 2 and 3 is automatically maintained in the best tracking state. At this time, the control signal detection circuit 11 has detected the reproduction control signal d from the control head 10, and accordingly, the phase control circuit 9 performs the above operation or the speed command signal generation circuit 21.
Outputs a constant speed command signal h.
The frequency-voltage conversion circuit 7 controls the speed of the capstan motor 5 so that the capstan motor 5 rotates at a rotational speed at which the magnetic tape 1 runs at the same speed as the speed at the time of recording by the recording / reproducing apparatus. Is set. Less than,
The rotation speed of the capstan motor 5 is the reference rotation speed.
v ₀ and good, the value of the speed command signal h at this time that the initial fixed value.

Next, the operation of this embodiment when the long-period control signal is missing on the magnetic tape 1 or the control signal is not recorded will be described with reference to FIG. However, FIG. 3 is a waveform diagram showing signals of respective parts in FIG. 1, and signals corresponding to FIG. 1 are denoted by the same reference numerals.

When the control head 10 reproduces and scans an area of the magnetic tape 1 where no control signal is recorded, the control signal detection circuit 11 stops detecting the control signal d, and the period during which the control signal d is not detected is a predetermined time (for example, the number of control signals d). Control signal g is generated. By this control signal g, the phase control circuit 9 establishes a predetermined constant signal (a predetermined phase relationship between the reproduction control signal d and the phase reference signal c,
(The signal output when there is no phase error).

When the control signal is no longer reproduced from the magnetic tape 1 and the phase control circuit 9 is set to the above-mentioned aggressive state and the phase control of the capstan motor 5 is stopped, the characteristic of the frequency-voltage conversion circuit 7 is changed to a speed command signal generation circuit. twenty one
The speed control of the capstan motor 5 by setting the speed command signal h from the controller to the initial fixed value makes it impossible to maintain the rotating heads 2 and 3 in the best tracking state. A few scanning states gradually deviate from the best tracking state, and the detection level of the constant amplitude signal decreases. In order to prevent this, the rotating head 2,
It is necessary to change the rotation speed of the capstan motor 5 so that 3 is in the best tracking state. Therefore, when the control signal g is output from the control signal detection circuit 11, the operation of the speed command signal generation circuit 21 is started, and the speed command signal h is initialized by the control signal f output from the arithmetic processing circuit 17. The rotation speed of the capstan motor 5 is made to be different from the reference rotation speed v ₀ by changing the characteristic of the frequency-voltage conversion circuit 7 by changing from the fixed value.

The operation of the arithmetic processing circuit 17 is the same as above, and when the arithmetic processing circuit 17 outputs the control signal f, the speed command signal generating circuit 21 increases or decreases the speed command signal h by a fixed amount from the initial fixed value, frequency - changing the characteristics of the voltage conversion circuit 7 fixed amount Δv only increase or decrease the rotational speed of the capstan motor 5 from the reference speed v ₀ and.
The direction of increase or decrease of the rotation speed is determined by the control signal f output from the arithmetic processing circuit 17.

Then, when the control signal is not reproduced from the magnetic tape 1 and the phase control circuit 9 is in the above-mentioned aggressive state, the phase control of the capstan motor 5 is not performed and the tracking state of the rotary heads 2 and 3 changes. Then, the arithmetic processing circuit 17 detects a decrease in the detection level of the constant amplitude signal and outputs the control signal f. Assuming that the control signal f is to increase the rotational speed of the capstan motor 5, a speed command signal generating circuit 21
There occurs a speed command signal h, which by the connexion frequency - characteristic of the voltage control circuit 7 changes the rotational speed of the capstan motor 5 is changed from v ₀ v to ₀ + Delta] v. Accordingly, the running speed of the magnetic tape 1 also increases, and the tracking state of the rotary heads 2, 3 changes.

When the detection level of the constant-amplitude signal detected by the arithmetic processing circuit 17 increases sequentially with the change of the tracking state of the rotating heads 2, 3, the rotating heads 2, 3
The tracking state of No. 3 has shifted to the best tracking state. At this time, the control signal f is not output from the arithmetic processing circuit 17 and the rotation speed of the capstan motor 5 is maintained at v ₀ + Δv. You.

On the other hand, when the detection speed of the constant amplitude signal sequentially decreases as a result of the rotation speed of the capstan motor 5 being set to v ₀ + Δv as described above, the scanning state of the rotating heads 2 and 3 is the best. This means that the state has shifted in the opposite direction, and the arithmetic processing circuit 17 outputs a control signal f for decreasing the rotation speed of the capstan motor 5. As a result, the speed command signal generating circuit 21 generates the speed command signal h, and changes the rotation speed of the capstan motor 5 to the reference rotation speed v _0.
Is switched to v ₀ −Δv lower than Δv by Δv.

Thus, the rotation speed of the capstan motor 5 becomes v ₀ + Δ
When set to v or v ₀ -Δv, the scanning state of the rotating heads 2 and 3 changes, and when this is the best tracking state, the detection level of the constant amplitude signal, which has increased so far, decreases. The control signal f is output from the arithmetic processing circuit 17 to switch from the rotation speed of the capstan motor 5 to v ₀ + Δv to v ₀ −Δv or vice versa, and thereafter, this switching is repeated. This allows
The scanning state of the rotary heads 2 and 3 is maintained in the best tracking state where the detection level of the constant amplitude signal is near the maximum.

In this way, even if the control signal is not reproduced from the magnetic tape 1 for a long time, the scanning state of the rotary heads 2 and 3 can be maintained in the best tracking state.

By the way, according to the speed control of the capstan motor 5, the scanning state of the rotary heads 2 and 3 is not fixed to the best tracking state, but is maintained in a state of fluctuating before and after this. In addition, as shown in FIGS. 2 and 3e, the envelope of the constant amplitude signal increases and decreases even in the best tracking state. To prevent this and maintain the scanning state of the rotary heads 2 and 3 in the best tracking state, the following method may be used.

That is, in this method, the scanning state of the rotary heads 2 and 3 becomes the best tracking state by sequentially changing the rotation speed of the capstan motor 5 one step at a time and sequentially changing the running speed of the magnetic tape 1. The rotation speed of the capstan motor 5 is set. Assuming that the amount of change in the rotation speed of the capstan motor 5 in one step is Δv, the rotation heads 2 and 3 are successively changed by this rotation speed.
When the scanning state changes in the direction of the best tracking state, the detection level of the constant amplitude signal increases every time the rotation speed of the capstan motor 5 changes by Δv, but the rotation speed becomes Δv. The amount of change in the detection level when it changes only decreases as the scanning state of the rotary heads 2 and 3 approaches the best tracking state, and becomes zero when the tracking state becomes the best. Conversely, when the scanning state of the rotating heads 2 and 3 changes in the direction away from the best tracking state, the amount of change in the detection level of the constant amplitude signal when the rotation speed of the capstan motor 5 changes by Δv is:
The larger the scanning state of the rotary heads 2 and 3 is, the greater the distance from the best tracking state is.

Therefore, when the detection level of the constant amplitude signal decreases after the phase control circuit 9 is set to the above-described aggressive state, the arithmetic processing circuit 17 outputs the control signal f and outputs the control signal f from the speed command signal generation circuit 21. The speed command signal h is changed by a fixed value from the initial fixed value, and the rotation speed of the capstan motor 5 is changed by Δv from the reference rotation speed v ₀ . This change direction (that is, increase or decrease) may be any direction, and is determined by the control signal f output from the arithmetic processing circuit 17.

The arithmetic processing circuit 17 detects and holds the amount of change in the detection level of the constant amplitude signal due to the change in the rotation speed of the capstan motor 5, and outputs a control signal f again to reduce the rotation speed of the capstan motor 5. From v ₀ + Δv, Δv is further changed in the same direction as above. As a result, the rotation speed of the capstan motor 5 becomes v ₀ + 2 × Δv. Then, the arithmetic processing circuit 17 detects the amount of change in the detection level of the constant amplitude signal due to the change in the rotation speed, and holds this,
The magnitude relationship between this variation and the previously detected variation is compared.

Here, the increasing variation Δv is positive, and the decreasing variation Δ
When v is negative and α ₀ = (current change amount-previous change amount) / Δv, when Δv> 0, when α = −α ₀ , Δv <0,
Define the increase rate α such that α = α ₀ .

When the arithmetic processing circuit 17 detects the amount of change in the detection level of the constant amplitude signal, it calculates an increase rate α. When the increase rate α is positive, the rotational speed of the capstan motor 5 is further increased by Δv in the same direction as the previous time. The control signal f is output to change the rotation speed of the capstan motor 5 by Δv in the direction opposite to the previous one when the increase rate α is negative.

Therefore, assuming that the detection level of the constant amplitude signal is sequentially increasing when the rotation speed of the capstan motor 5 is sequentially increasing by Δv, the rotation speed of the capstan motor 5 is equal to the rotation head 2. , 3 scanning direction is changing to the best tracking state,
The sequential change in the detection level of the constant amplitude signal decreases and the increase rate α is kept positive. And the rotating head 2,
When the scanning state 3 becomes almost the best tracking state, the variation of the detection level of the constant amplitude signal becomes almost zero, and the variation of the above-mentioned detection level detected last time and this time becomes almost equal, and the increase rate α is almost zero. Becomes When the increase rate α (> 0) becomes equal to or smaller than a sufficiently small threshold value, the arithmetic processing circuit 17 rotates the capstan motor 5 at a rotational speed that sets the scanning state of the rotating heads 2 and 3 to the best tracking state. Output of the control signal f is stopped.

If, as a result of increasing the rotation speed of the capstan motor 5 by Δv, the scanning state of the rotary heads 2 and 3 deviates from the best tracking state, the detection level of the constant amplitude signal detected by this is detected. The amount of change becomes larger than that detected last time, and as a result, the increase rate α becomes negative. At this time, the arithmetic processing circuit 17 changes the rotational speed of the capstan motor 5 in the opposite direction, that is, in the decreasing direction by Δv, and when the increase rate α becomes positive, the The rotation speed of the pusher motor 5 is sequentially reduced by Δv until the increase rate α becomes equal to or less than the threshold value.

In this way, the rotational speed of the capstan motor 5 can be set to a value that makes the scanning state of the rotary heads 2 and 3 the best tracking state or a state that is very close thereto, and maintains this value. be able to. Therefore,
The video signal is reproduced from the magnetic tape 1 at the maximum level or at a constant level near the maximum level.

In addition, the increase rate α is not limited to the above, and may be −
If it is possible to determine whether or not the scanning state of the rotary heads 2 and 3 is becoming the best tracking state, such as (the change amount of the detection level detected this time−the change amount of the detection level detected last time). Good.

The detection of the change in the detection level of the constant amplitude signal in the arithmetic processing circuit 17 is performed after the capstan motor 5 has sufficiently responded to the output control signal f and the rotation cycle of the drum motor 4 Is performed at a timing synchronized with.

FIG. 4 is a block diagram showing another embodiment of the servo control device of the recording / reproducing apparatus according to the present invention, wherein 22 is a frequency divider,
23 is a reference signal generation circuit, 24 and 25 are switches,
Parts corresponding to those in the drawings are denoted by the same reference numerals, and redundant description is omitted.

In the figure, the characteristics of the frequency-voltage conversion circuit 7 are fixed so that the capstan motor 5 rotates at the reference rotation speed. The switches 24 and 25 are controlled by a control signal g output from the control signal detection circuit 11. When the control signal d is reproduced from the magnetic tape 1 by the control head 10, the switches 24, 2
5 closes to the A side and operates in the same manner as the embodiment shown in FIG.

When the control signal is not reproduced from the magnetic tape 1 for a long time, the switches 24 and 25 are closed to the B side. The operation in this case will be described with reference to FIG. FIG. 5 is a waveform diagram showing signals of respective parts in FIG. 4, and signals corresponding to FIG. 4 are denoted by the same reference numerals.

The FG signal i output from the frequency generator 6 is frequency-divided by a frequency divider 22 having an appropriate frequency division ratio.
Is supplied to the phase control circuit 9 via the. Further, the reference signal generating circuit 23 generates a reference frequency signal k based on the output of the reference oscillator 18, and this reference frequency signal k is a switch.
It is supplied to the phase control circuit 9 via 25. In the phase control circuit 9, the frequency-divided output j of the frequency divider 22 and the reference frequency signal k
And a speed control signal is generated, and added to the output signal of the frequency-voltage conversion circuit 7 to control the speed of the capstan motor 4.

On the other hand, the arithmetic processing circuit 17 detects the detection level of the reproduced constant amplitude signal in the same manner as in FIG. 1, and outputs the control signal f in the direction in which the detection level becomes the maximum to output the control signal f. By controlling the signal generation circuit 23, the frequency of the reference frequency signal k is changed stepwise. When the frequency of the reference frequency signal k changes, the frequency relationship between the reference frequency signal k and the frequency-divided output j of the frequency divider 22 changes, so that the rotation speed of the capstan motor 5 changes, and the rotation heads 2, 3 The positional relationship between the scanning trajectory and the video track changes to achieve the best tracking state.

In this embodiment, the characteristic of the frequency-voltage conversion circuit 7 is changed to change the rotation speed of the capstan motor 5 in the embodiment shown in FIG. The rotation speed of the capstan motor 5 is fixed by means of the frequency divider 22, the reference signal generation circuit 23, and the phase control circuit 9 which are fixed.

In this embodiment, the servo control system of the capstan mode 5 in the recording mode, like the ordinary VTR,
By synchronizing the phase of the FG signal from the frequency generator 6 and the output signal of the reference signal generating circuit 19, the traveling speed of the magnetic tape can be set within a specified range (usually within about ± 20% of the specified value). I have. Therefore, in this embodiment having the above configuration, at least the frequency of the reference frequency signal k output from the reference signal generation circuit 23 is made equal to the reference phase signal c 'output from the reference signal generation circuit 19. The traveling speed of the magnetic tape 1 can be ensured within the above-specified range. As a result, more accurate and stable tracking control becomes possible.

FIG. 6 is a block diagram showing still another embodiment of the servo controller of the recording / reproducing apparatus according to the present invention.
Is an electro-mechanical conversion element, 28 is a position control circuit, and 29 is an arithmetic processing circuit, and portions corresponding to those in FIG.

In the figure, the rotating heads 2 and 3 are respectively displaced in a direction perpendicular to the longitudinal direction of the video track on the magnetic tape 1 by electro-mechanical conversion elements 26 and 27 which are actuators constituted by, for example, bimorph plates. Mounted on a rotating drum where possible.

The arithmetic processing circuit 17 detects the detection level of the reproduced constant amplitude signal as in FIG. 1, and outputs a control signal f indicating the direction in which the detected level is maximum. Each time the control signal f is supplied, the position control circuit 28 controls the electro-mechanical transducers 26 and 27 to move the rotary heads 2 and 3 in the direction in which their scanning trajectories coincide with the video track. Displace step by step.

The output signal of the position control circuit 28 is supplied to the arithmetic processing circuit 29. The arithmetic processing circuit 29 detects the average value of the output signal of the position control circuit 28 and controls the capstan motor 5 in the same manner as in the embodiment shown in FIG. 1 so that the average value becomes zero. .

Therefore, the capstan motor 5 by the arithmetic processing circuit 29
The tracking control for eliminating the low frequency disturbance including the drift component is performed by the control of the position control circuit 28, and the average value of the output signal of the position control circuit 28 is changed to the dynamic range of the rotating heads 2 and 3 by the electro-mechanical conversion elements 26 and 27. The rotation heads 2 and 3 respond quickly to a high-frequency component of the output signal of the position control circuit 28 due to the bending of the video track and the like, and the rotation heads 2 and 3 center around the center of the dynamic range. Displace.

In this way, high-performance and stable tracking control can be realized.

Such a configuration can be applied to the embodiment shown in FIG. 4, and an embodiment in this case is shown in FIG. The operation of the embodiment shown in FIG. 7 is clear from the description of the operation of the embodiment shown in FIGS. 4 and 6, and a description thereof will be omitted.

FIG. 8 is a block diagram showing still another embodiment of the servo controller of the recording / reproducing apparatus according to the present invention.
Is a rotary head, 32 is a preamplifier, 33 is a demodulation circuit, 34 is an output terminal, and 35 is an arithmetic processing circuit. The parts corresponding to those in FIGS. .

This embodiment is applied to a VTR having a Hi-Fi audio function, such as a home VTR of the VHS system or the S-VHS system.

In FIG. 8, in the video track forming area of the magnetic tape 1, a video track is formed in a shallow layer and an audio track in which a frequency-modulated audio signal is recorded in a deep layer. In addition, on the rotating drum,
The rotating heads 2 and 3 for video signals are provided so as to be displaceable by the mechanical conversion elements 26 and 27 as described above, and the rotating heads 30 and 31 for audio signals are fixedly provided.

The rotating heads 2 and 3 reproduce a video signal from a video track in a shallow layer of the magnetic tape 1 as in the above embodiments. This video signal is processed by the preamplifier 14 and the reproduction processing circuit 15 as in the above embodiments. The rotating heads 30 and 31 reproduce a frequency-modulated audio signal from an audio track in a deep layer of the magnetic tape 1. These rotating heads 3
The audio signals from 0 and 31 are amplified by a preamplifier 32 and synthesized by a switching signal generated from a tack signal b, then demodulated by a demodulation circuit 33 and output from an output terminal 34.

In such a configuration, the arithmetic processing circuit 35 includes a preamplifier
The frequency-modulated audio signal output from 32 is supplied, and the capstan motor 5 is controlled using this audio signal as a constant amplitude signal, similarly to the arithmetic processing circuit 17 in the previous embodiment. Thereby, the frequency-modulated audio signal has the maximum amplitude, that is, the rotating heads 30, 31
The tracking control is performed so that the scanning trajectory coincides with the audio track on the magnetic tape 1 to achieve the best tracking state.

The arithmetic processing circuit 17 and the position control circuit 28 process the constant amplitude signal output from the preamplifier 14 to control the electro-mechanical conversion elements 26 and 27, as in the embodiment shown in FIG. The tracking control is performed such that the rotating heads 2 and 3 are in the best tracking state.

In this way, the rotating heads 2, 3 and the rotating heads 30, 31 are both in the best tracking state.

The control of the capstan motor 5 in FIG.
Although it is the same as the drawing, as shown in FIG. 9, the control of the capstan motor 5 may be performed as shown in FIG.

FIG. 10 is a block diagram showing still another embodiment of the servo control apparatus of the recording / reproducing apparatus according to the present invention, in which reference numeral 36 denotes a switch, 37 denotes a control signal generation circuit, and portions corresponding to FIG. The same reference numerals are given and duplicate explanations are omitted.

This embodiment can record a control signal on a magnetic tape when it is known that the control signal has been missing for a long time or has not been recorded at all on a recorded magnetic tape. It was made.

In FIG. 10, the switch 36 is operated by the user, and when the switch 36 is closed to the C side, the first
The configuration is the same as that of the embodiment shown in FIG.

On the other hand, when the switch 36 is closed to the D side, when the magnetic tape 1 is run and the video signals are reproduced by the rotating heads 2 and 3, the control signal generating circuit 11 does not detect the control signal. As in the embodiment shown in FIG. 1, the phase control circuit 9 is set to the above-mentioned aggressive state, the speed command signal generation circuit 21 operates, and the capstan is controlled under the control of the arithmetic processing circuit 17. The speed of the motor 5 is controlled, and the scanning state of the rotary heads 2 and 3 is set to the best tracking state.

In this state, the control signal generating circuit 37 generates a control signal d 'based on the phase reference signal a output from the reference signal generating circuit 19, and the control signal d' is transmitted via the switch 36 to the control head d. 10 and is recorded on a control track on the magnetic tape 1.

As described above, the magnetic tape 1 is reproduced while reproducing the video signal in the tracking state where the scanning state of the rotary heads 2 and 3 is the best.
The control signal can be recorded in the control signal. Since the control signal is recorded in this manner, the positional relationship between the control signal and the video track is equal to the positional relationship between the control signal and the video track which are simultaneously recorded in the recording mode, and therefore, as in this embodiment. When reproducing a magnetic tape on which a control signal has been recorded, the control signal is used to control the phase of the capstan motor, so that the scanning state of the rotating head is maintained in the best tracking state. Become.

Therefore, when it is known that the control signal has been lost for a long time or the control signal has not been recorded on the recorded magnetic tape 1, the switch 36 is switched to the D side to switch the entire recording portion of the magnetic tape. By performing the reproduction, the control signal can be recorded over the entire recording portion. Therefore, the magnetic tape on which the control signal is recorded as described above can be favorably reproduced by any other VTR.

In the embodiment shown in FIGS. 4 and 6 to 9 as well, the control signal generating circuit 37 and the switch 36 are provided as in the embodiment shown in FIG. The control signal can be recorded on the tape.

[Effects of the Invention] As described above, according to the present invention, a control signal is lost for a long time due to a failure in a control signal recording processing system or a control head, or the control signal is not recorded at all. The recorded state of the magnetic tape can be reproduced by setting the scanning state of the rotating head to the best tracking state, so that the already recorded software is not wasted.

Further, according to the present invention, a new control signal can be recorded on the recorded magnetic tape, and the magnetic tape can be restored to a regular recording format, thereby enabling good reproduction by any recording / reproducing apparatus. And

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a servo control device of a recording / reproducing apparatus according to the present invention, FIGS. 2 and 3 are waveform diagrams showing signals of respective parts in FIG. 1, and FIG. FIG. 5 is a block diagram showing another embodiment of the servo controller of the recording / reproducing apparatus according to the present invention, FIG. 5 is a waveform diagram showing signals of respective parts in FIG. 4, and FIGS. FIG. 13 is a block diagram showing still another embodiment of the servo control device. 1 ... Magnetic tape, 2,3 ... Rotating head, 5 ... Capstan motor, 6 ... Frequency generator, 7 ... Frequency-voltage conversion circuit, 9 ... Phase control circuit, 10 ... Control head , 11 control signal detection circuit, 17 arithmetic processing circuit, 19 reference signal generation circuit, 20 variable delay circuit, 21 speed command signal generation circuit, 22 frequency divider, 23
… Reference signal generation circuit, 24,25… Switch, 26,27… Electro-mechanical conversion element, 28… Position control circuit, 29… Operation processing circuit, 30,31… Rotation head, 34… Sound Signal output terminal, 35: arithmetic processing circuit, 36: switch, 37: control signal generation circuit.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yuji Inaba 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. New Media Plant, Hitachi, Ltd. (56) References JP-A-55-157149 (JP, A) 1984-75453 (JP, A)

Claims (8)

(57) [Claims] A recording medium is run by a capstan motor, and a video track formed obliquely on the recording medium is scanned by a rotary head to reproduce a video signal. Generating a speed control signal from a frequency signal having a frequency according to the frequency-voltage conversion means, and generating a phase control signal from the control signal and the phase reference signal reproduced from the recording medium by the phase control means; A servo control device for a recording / reproducing apparatus, wherein said capstan motor is controlled by a control signal and said phase control signal. An arithmetic processing means for generating and outputting a control signal; and detecting that the control signal is not reproduced from the recording medium for a predetermined period or more. Control signal detection means for outputting a signal; and speed control means for operating during the signal period of the detection signal and for controlling the speed of the capstan motor in accordance with the control signal output from the arithmetic processing means. During the period in which the control signal is not reproduced from the medium for the predetermined period or more, the rotation speed of the capstan motor is changed so that the best tracking state in which the video signal is reproduced with the maximum amplitude from the rotation head can be set. A servo control device for a recording / reproducing device, characterized in that: 2. The frequency control device according to claim 1, wherein the speed control unit includes: a frequency signal generation unit; and a frequency-voltage conversion unit whose conversion characteristic changes according to the control signal output from the arithmetic processing unit. Wherein the phase control means is set to an output state of a constant level signal in accordance with the detection signal. 3. The frequency control device according to claim 1, wherein the speed control unit includes: a frequency signal generation unit; a frequency-voltage conversion unit having a fixed conversion characteristic; a frequency division unit that divides the frequency signal; Reference signal generating means for outputting a reference signal whose frequency changes in accordance with the control signal output by the arithmetic processing means; and generating a signal corresponding to a frequency difference between the output signal of the frequency dividing means and the reference signal. The phase control means for outputting the output signal of the frequency-voltage conversion means and the output signal of the phase control means. The output signal of the addition means is used to control the speed of the capstan motor. A servo control device for a recording / reproducing device, which is a signal. 4. The rotating head according to claim 1, 2 or 3, wherein the rotating head is displaceable in a direction perpendicular to a longitudinal direction of the video track on the recording medium by an electro-mechanical converting means. A position control means for generating and outputting a control signal of the electro-mechanical conversion element according to the control signal output from the arithmetic processing means; and a control signal output from the position control means. Second arithmetic processing means for detecting and generating a control signal for making the average value a predetermined constant value, and outputting the control signal according to the control signal output from the position control means. While displacing the rotating head in the above direction,
The speed control means controls the speed of the capstan motor in response to the control signal output from the second arithmetic processing means, so that the rotary head is controlled by the control signal output from the position control means. A servo control device for a recording / reproducing apparatus, wherein the displacement of the rotary head is performed about a center position of a movable range of the rotary head by the electro-mechanical conversion element. 5. A recording medium in which a video track is formed obliquely in a shallow layer and an audio track is formed in a deep layer in parallel with the video track is driven by a capstan motor, and electro-mechanical conversion is performed on a rotating drum. A video signal is reproduced from the video track by a first rotating head mounted displaceably in a direction perpendicular to the longitudinal direction of the video track by means, and fixedly mounted on the rotating drum. When reproducing an audio signal from the audio track by the second rotary head, a speed control signal is generated by frequency-voltage conversion means from a frequency signal having a frequency corresponding to the rotation speed of the capstan motor; and A phase control signal is generated by the phase control means from the control signal reproduced from the recording medium and the phase reference signal, and the phase control signal is generated by the speed control signal and the phase control signal. A servo control device of the magnetic recording / reproducing apparatus for controlling the capstan motor by envelope detection of a video signal reproduced by the first rotary head and generating a first control signal for increasing a detection level. First arithmetic processing means for generating and outputting; position control means for controlling the electro-mechanical conversion means in accordance with the first control signal to displace the first rotary head; and Second arithmetic processing means for envelope-detecting the reproduced audio signal by the rotating head, generating and outputting a second control signal for increasing the detection level, and the control signal not being reproduced from the recording medium for a predetermined period or more. Control signal detection means for detecting the detection signal and outputting a detection signal; and operating for a signal period of the detection signal, and responding to the second control signal output from the second arithmetic processing means. Speed control means for controlling the speed of the capstan motor by changing the rotation speed of the capstan motor for a period equal to or longer than the predetermined period during which the control signal is not reproduced from the recording medium. The first tracking state in which the audio signal is reproduced from the head at the maximum amplitude, and the first means is controlled by controlling the electromechanical conversion means.
A servo control device for a recording / reproducing apparatus, wherein a best tracking state in which a video signal is reproduced with a maximum amplitude from a rotating head can be set. 6. The speed control unit according to claim 5, wherein the speed control unit changes the conversion characteristic according to the second control signal output from the frequency signal generation unit and the second arithmetic processing unit. And a frequency-to-voltage conversion means, wherein the phase control means is set to an output state of a constant level signal in accordance with the detection signal. 7. The frequency control device according to claim 5, wherein the speed control unit includes: a frequency signal generation unit; a frequency-voltage conversion unit having a fixed conversion characteristic; a frequency division unit that divides the frequency signal; A reference signal generating means for outputting a reference signal whose frequency changes in accordance with the second control signal output by the second arithmetic processing means; and a frequency difference between the output signal of the frequency dividing means and the reference signal. The phase control means for generating and outputting a corresponding signal; and an addition means for adding an output signal of the frequency-voltage conversion means and an output signal of the phase control means, and outputting the output signal of the addition means to the key. A servo control device for a recording / reproducing device, which is used as a speed control signal of a pusher motor. 8. A control head generating means for outputting a control signal having a predetermined positional relationship with the rotation of the rotary head according to claim 1, 2, 3, 3, 4, 5, 6, or 7, A servo control device for a recording / reproducing apparatus, wherein the control signal is recorded on the recording medium being reproduced.