JP2825170B2 - Tape speed controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to tape speed control for a recording / reproducing apparatus such as a VTR.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram of a conventional tape speed control device described in, for example, JP-A-63-71963. 1 is a magnetic tape as a recording medium, 2 is a capstan shaft, 3 is a capstan motor for rotating the capstan shaft 2 , and a magnetic pole (hereinafter, referred to as FG) is provided on a rotor outer peripheral surface 3a.
) Is magnetized over the entire circumference. Reference numeral 4 denotes a pinch roller, and the magnetic tape 1 is conveyed while being held between the pinch roller 4 and the capstan shaft 2 by pressure. Reference numeral 5 denotes a rotation sensor disposed at a minute distance from the rotor outer peripheral surface 3a of the capstan motor 3, detects a FG of the rotor outer peripheral surface 3a, and outputs a sine wave signal (hereinafter referred to as an FG signal). Output. 6 is an amplifier circuit for amplifying the FG signal, 7 is a waveform shaping circuit for converting the output of the amplifier circuit 6 into a rectangular wave, 8 is a speed control for comparing the FG signal with a reference signal and outputting an error thereof as an error signal. A circuit 9 is a motor drive circuit for driving the capstan motor 3 to rotate.

Next, the operation will be described. The magnetic tape 1 held between the capstan shaft 2 and the pinch roller 4
When the capstan motor 3 rotates, the capstan motor 3 is driven to travel by the capstan shaft 2 that rotates integrally therewith. At this time, an FG signal corresponding to the rotation speed of the capstan motor 3 is output from the rotation sensor 5, and the signal is input to the speed control circuit 8 via the amplifier circuit 6 and the waveform shaping circuit 7. The speed control circuit 8 compares the frequency of the reference signal and the frequency of the FG signal, outputs an error signal to the motor drive circuit 9, and rotates the motor at a predetermined speed. That is, the magnetic tape 1 held between the capstan shaft 2 and the pinch roller 4
The vehicle is driven at a constant speed.

Since the conventional tape speed control device is constructed as described above, the running speed of the magnetic tape 1 is detected by using the FG magnetized on the rotor outer peripheral surface 3a of the capstan motor 3, and this cap speed is detected. The tape was driven at a constant speed by keeping the rotation speed of the stun motor constant. Generally, in order to accurately detect the traveling speed of the magnetic tape 1, an FG signal of several hundred Hz to several kHz is required. In order to magnetize the corresponding FG on the rotor outer peripheral surface 3 a of the capstan motor 3, However, there has been a problem that the diameter of the rotor is inevitably increased, which is not suitable for downsizing the entire apparatus. Further, as holding the magnetic tape 1 by the capstan shaft 2 and the pinch roller 4, for crimping, especially when using thin magnetic tape may be damaged, such as partially or elongation There was a problem.

[0005] improvement in order to solve the problems such as the above Symbol
As a proposal, a tape speed control device that accurately detects the running speed of the magnetic tape without using a capstan shaft and a pinch roller to drive the running of the magnetic tape, and is suitable for miniaturization.
Has been proposed.

The improved tape speed control device comprises a recording head for recording a speed control signal on a magnetic tape, a reproducing head for reproducing the signal at a position separated by a predetermined distance backward in the tape running direction, and A phase comparison circuit for detecting a phase difference between the recording side speed control signal and the reproduction side speed control signal of the two heads, and a reel motor for driving the magnetic tape based on the phase difference are provided.

Further, the recording head and the reproducing head are constituted by one block. Further, the recording head and the reproducing head is shall respectively disposed by a distance of 1/2 spaced position of the recording wavelength determined by the frequency of the desired tape speed and the speed control signal.

[0008]

SUMMARY OF THE INVENTION The conventional improvement plan is as described above.
The capstan shaft and pinch
It is possible to drive the magnetic tape independently of the roller
However, if the speed of the magnetic tape is 1/3 or 1 of the desired speed
When the speed becomes / 5, the speed is mistaken for the desired speed.
Possible and also controls the speed of the magnetic tape with high precision
There was a problem that it was not possible. The present invention
It was made to solve such problems.
You.

[0009]

SUMMARY OF THE INVENTION Tape speed control of the present invention
The device uses a magnetic tape as a recording medium for audio and video
In a magnetic recording and reproducing apparatus for recording and reproducing signals,
Speed control signal for controlling the running speed of the
First and second recording on the magnetic tape at a given frequency
Recording head and tape running for each of the above recording heads
At a position separated by a predetermined distance behind the direction
Recorded on the magnetic tape by the recording heads.
First and second reproduction heads for reproducing the speed control signal
And the speed control signal reproduced by the first reproducing head and the first
Phase difference with the speed control signal recorded by the recording head
The first phase comparison circuit that performs
Speed control signal and speed control for recording by the second recording head
A second phase comparison circuit for detecting a phase difference with the signal;
And an adder for adding the output of the second phase comparison circuit.
A reel motor for driving and driving the magnetic tape;
Control means for controlling the reel motor based on the output of the
And a step. Further, those having a delay circuit for delaying both subsequent reproducing head, or one to the speed control signal for reproducing the pre-stage and the speed control signal of the recording head for recording a speed control signal.

[0010]

[Action] tape speed control apparatus of the present invention, first,
Two different frequencies recorded by the second recording head
And the speed control signals reproduced by the first and second reproducing heads are compared by the first and second phase comparators , respectively , based on the outputs of the two phase comparators.
Controls the rotation of the reel motor, preventing malfunctions.
As a result, stable speed control becomes possible.

In the tape speed controller of the present invention, a speed control signal recorded by a recording head is delayed by a delay circuit, or a speed control signal reproduced by a reproduction head is delayed by a delay circuit. As a result, the tape speed is variably controlled with respect to the desired speed.

Hereinafter, a configuration serving as a base of the present invention will be described with reference to the drawings . In Figure 1, 1 is a magnetic tape as a recording medium, 12 is a tape reel for accommodating winding of the magnetic tape 1, 13 are fitting engagement in the tape reel 12, reel motor for it times <br/> rotation, The rotation of the reel motor 13 drives the magnetic tape 1 to be wound around the tape reel 12. Reference numeral 14 denotes a recording head for recording a speed control signal of a single frequency, and 15 denotes a reproducing head for reproducing the speed control signal recorded by the recording head 14. A desired tape speed and speed are provided behind the tape of the recording head 14. It is provided at a position separated by a distance equal to の of the recording wavelength determined by the frequency of the control signal. Reference numeral 16 denotes a crystal, and 17 denotes a crystal oscillation circuit, which generates a tape speed control signal recorded by the recording head 14 based on the oscillation frequency of the crystal 16. Reference numeral 18 denotes a recording amplifier circuit for recording a speed control signal by the recording head 14, and 19 denotes a reproducing head 15
A reproduction amplifier circuit that amplifies the minute signal reproduced at
Reference numeral 20 denotes a waveform shaping circuit for converting the output of the reproduction amplifier circuit 19 into a rectangular wave. 21 output of the crystal oscillation circuit 17 and the waveform shaping circuit 20 are inputted, respectively, in the phase comparator circuit as much phase is the ratio <br/> compare outputs tape speed error signal from the comparison error. 22 is an integrator for smoothing this speed error signal, and 23 is a motor drive circuit.

Next, the operation will be described. Magnetic tape 1
Is recorded with a speed control signal of a frequency set by the crystal 16 and the crystal oscillation circuit 17, and this frequency is used when reproducing a signal on the magnetic tape 1 to obtain an image, and the image swings due to a tape speed error. 720 (Hz), which is an integral multiple of the field frequency of the TV signal, is selected so that the signal is hardly noticeable.
Recorded above. On the other hand, the speed control signal recorded on the magnetic tape 1 is immediately reproduced by the reproduction head 15, amplified by the reproduction amplifier circuit 19 and the waveform shaping circuit 20, subjected to rectangular wave processing, and input to the phase comparison circuit 21. You. This phase comparator circuit 21 is input the speed control signal recording side generated by a crystal oscillator circuit 17 at the same time, the speed error signal is generated by position phase of the two signals are compared. This speed error signal is smoothed by the integrator 22 and drives the reel motor 13 via the motor drive circuit 23 so that the running speed of the magnetic tape 1 becomes constant.

Here, the mechanism for generating the speed error signal will be described in detail. First, the principle of detecting the tape running speed will be described. To detect the traveling speed of the magnetic tape 1 using the recording head 14 and the reproducing head 15,
The speed control signal is transmitted through the recording head 14 to the read head 1
It is sufficient to measure the time until reproduction is performed in step 5. As a method to achieve this, various methods such as using a timer can be considered, how that can be realized with good Ri simple configuration will be described with reference to FIG. In the figure, (a) is a speed control signal recorded by the recording head 14, (b),
(C) and (d) are speed control signals reproduced by the reproducing head 15, respectively . Record head 14 and the read head 15
Is set to 1/2 of the recording wavelength determined by the desired tape speed and the frequency of the recording side speed control signal. For example, if the tape is running at the desired speed, As shown in (a) and (b), the phase relationship between the side speed control signal and the reproduction side speed control signal requires a time t ₀ from the recording of the speed control signal to the reproduction thereof, and the phase is just inverted. It will be in the state of having done. When the tape is running at a speed higher than the desired speed, the relationship between (a) and (c) is established, and it takes a time t ₁ (t ₁ <t ₀ ) from recording to reproduction. Conversely, when the tape is running at a speed lower than the desired speed, the relationship between (a) and (d) is established, and it takes a time t ₂ (t ₂ > t ₀ ) from recording to reproduction. As described above, the speed error signal of the magnetic tape 1 can be obtained by comparing the phases of the recording side speed control signal and the reproduction side speed control signal. That is, if the reel motor is controlled so that the phases of the recording-side speed control signal and the reproduction-side speed control signal are inverted, the magnetic tape 1 can be run at a desired speed and at a constant speed.

Next, how the speed error signal is generated will be described with reference to FIG. (A) is a speed control signal recorded by the recording head 14, (b) is a speed control signal reproduced by the reproducing head 15, (c) is the above-mentioned recording-side speed control signal and reproduction-side speed. A PWM wave-shaped speed error signal obtained by comparing the phase difference of the control signal by the phase comparison circuit 21, and (d) is a signal obtained by smoothing the PWM wave-shaped speed error signal by the integrator 22. Now, a description will be given of the generation of a speed error signal when the tape speed changes from a state faster than a desired value to a state slower. In the figure, section A is a state in which the tape speed is faster than a desired value, section B is a state in which the tape speed is slower than the desired value, and in section A, the speed error of the PWM wave corresponding to the speed error is below the neutral level. A signal is obtained. On the other hand, in the section B, a speed error signal of a PWM wave corresponding to the speed error is obtained above the neutral level, and this speed error signal (c) is smoothed by the integrator 22 and the direct current component (d) of the speed error signal is obtained. Get. That is, the output of the integrator 22 that smoothes the speed error signal outputs a low voltage when the tape speed is higher than a desired value, and outputs a high voltage when the tape speed is lower than the desired value.

Next, as another example , a speed control signal is recorded / recorded.
FIG. 4 shows a configuration in which the recording head 14 and the reproducing head 15 for reproducing are configured as one block. Other configurations,
The operation is the same as that of FIG. 1 described above. With this configuration, the recording head 14 and the reproducing head 15 can be arranged very close to each other , which is advantageous for miniaturization of the apparatus. As a practical problem, the recording frequency of the speed control signal is set to 720 Hz, and the running speed of the magnetic tape 1 is set to 99.9.
mm / s, the recording wavelength λ is λ = 99.9 / 720 = 0.139 mm. Since the distance L between the recording head 14 and the reproducing head 15 is の of this λ, L = 0.139 / 2. = 0.695 mm = 69.5 μm, which is a very small distance. However, if a thin film head or the like is used, the recording head 14 and the reproducing head 15 can be brought close to a very small distance.

[0017]

[Embodiment 1 ] Next , an embodiment of the present invention will be described with reference to the drawings. Figure 5 is a book
1 shows a configuration of a tape speed control device according to the present invention.
However, basically, two sets of the configuration of FIG. 1 are duplicated.
You. Explaining the difference, there are two fixed heads 14, 34 for recording / reproducing the speed control signal and two reproducing heads 15, 35, and the speed control signals of different single frequencies are used for the fixed heads 14, 34. Is recorded on the magnetic tape 1. Further, the fixed head 14 and the reproducing head 15,
The fixed head 34 and the reproducing head 35 are disposed at positions separated by different distances L ₁ and L ₂ , respectively, and these distances are determined by the desired tape speed and the recording wavelength determined by the speed control signal. Each is set to に. The speed control signals recorded by the fixed heads 14 and 34 having this configuration are immediately reproduced by the reproducing heads 15 and 35,
The recording-side speed control signal and the reproduction-side speed control signal are separately input to the phase comparison circuits 21 and 41. In the phase comparison circuits 21 and 41, speed error signals are generated according to the principle described with reference to FIG. 1 , and are smoothed by the integrators 22 and 42, added by the adder 50, and then added to the motor drive circuit. through 23 is controlled so as the reel motor 13 running speed of the magnetic tape 1 is constant.

According to this embodiment, the tape speed control device of the present invention can be operated more stably with respect to the conventional improvement . This will be described with reference to FIGS.
6A shows a recording-side speed control signal, and FIG.
(C) and (d) show the reproduction-side speed control signals, (b) shows the normal operation, and (c) and (d) show the timing of the malfunction. FIG.
As described above, when the magnetic tape 1 is running at a desired speed, the phases of the recording-side speed control signal and the reproduction-side speed control signal are in a reversed state. Therefore, with respect to the recording-side speed control signal (a), (b), (c), and (d) are all determined to be normal operations. However, actually, the relationship between (a) and (b) is normal, but (a) and (c) are 1/3 of the desired speed, and (a) and (d) are the desired speed. The relationship becomes 1/5. This malfunction can be detected when the speed control signal recorded by the recording head 14 is immediately reproduced by the reproducing head 15 where the servo should be locked at a half of the recording wavelength. Occurs when the servo is locked at the next edge or at the next edge.

[0019] However, this embodiment, since the recording / reproducing two different frequencies the speed control signal as shown in FIG. 7, the recording-side speed control signal 1 (a) and the reproduction-side speed control signal 1 (b ), The respective phases of the recording-side speed control signal 2 (c) and the reproduction-side speed control signal 2 (d) must be in an inverted state, and when these are satisfied, the magnetic tape 1 can run at a desired speed.

Embodiment 2 FIG. Next preceding recording head for recording a speed control signal as a second embodiment, both of the subsequent reproducing head for reproducing a speed control signal, the one provided a delay circuit for delaying a speed control signal with reference to FIG. 8 described I do. This embodiment is obtained by adding two delay circuits to the configuration of FIG. 1. Specifically, the recording-side speed control signal and the reproduction-side speed control signal
Delay circuit 1 (24) and delay circuit 2
(25) is inserted.

The operation in this configuration will be described below.
As described with reference to FIG. 1, the recording side speed control signal and the reproduction side in three cases: when the tape is running at a desired speed, when the tape is faster than the desired speed, and when the tape is slower than the desired speed. The phase relationship of the speed control signal is as shown in FIG. If the tape is running at a desired speed, the phase relationship between the recording-side speed control signal and the reproduction-side speed control signal is as shown in FIGS. It takes a time t ₀ until the signal is reproduced, and the phase is just inverted. If the tape is running faster than desired,
The relationship between (a) and (c) is established, and it takes a time t ₁ from recording to reproduction. Conversely, when the tape is running at a speed lower than the desired speed, the relationship between (a) and (d) is established, and it takes time t ₂ from recording to reproduction. In other words, it can be understood that the tape speed can be set arbitrarily by manipulating the time from when the speed control signal is recorded to when it is reproduced.
For example, when the tape is running at a speed higher than the desired tape speed shown in FIG. 2, the relationship between (a) and (c) is maintained, and the servo is controlled so that the relationship between (a) and (b) is maintained. You. Therefore, the recording-side speed control signal 2 (t ₀ -t ₁₎
If the servo is locked in this state after a delay by the time, the relationship between (a) and (c), that is, the tape can be run at a constant speed faster than the desired speed. Conversely, when the user wants to run at a speed lower than the desired speed, the relationship between (a) and (d) in the figure may be maintained, and the reproduction-side speed control signal is set to (t).
Only ₂ -t ₀₎ time it is sufficient to delay.

By delaying the recording-side speed control signal or the reproduction-side speed control signal by the delay circuit 1 (24) or the delay circuit 2 (25) as described above, a variable speed can be obtained with respect to a desired speed. Can be controlled at a constant tape speed. This makes it possible to correct a slight speed error in the actual tape speed relative to a desired tape speed due to an error in mounting distance or the like between the recording head and the reproducing head. The speed of the tape can be controlled during rewinding or searching.

[0023]

As described above, according to the present invention, the running speed of the magnetic tape can be controlled without using the capstan shaft and the pinch roller, so that it is suitable for miniaturization and when a thin tape is used. There is an effect that a tape speed control device capable of preventing tape damage can be obtained.

Further, disposing the recording head and the reproducing head for recording / reproducing speed control signal on a magnetic tape lever configure <br/> a single member, the recording head reproducing head in close proximity It can be, it is possible to FIG Rukoto the size of the apparatus
You.

Further, the distance between the recording head and the reproducing head for recording / reproducing speed control signal on a magnetic tape, if 1/2 of the recording wavelength determined by the frequency of the desired tape speed and the speed control signal, The running speed of the magnetic tape 1 can be detected with a simple circuit configuration .

The frequency of the speed control signal recorded on the magnetic tape is set to an integral multiple of the field frequency of the TV signal.
If so , it is possible to make it difficult for the image to fluctuate due to the tape speed error .

Further, two recording heads for recording a speed control signal on a magnetic tape and two reproducing heads for reproducing the signal are provided so that the frequency of the speed control signal recorded by each recording head is different. since the there is an effect that can prevent malfunctioning during a tape speed control.

Further, because of the provided pre-stage of the recording head for recording a speed control signal, both of the subsequent reproducing head for reproducing a speed control signal, or a delay circuit for one to delay the speed control signal, the running of the magnetic tape The speed can be varied, and the desired tape speed can be obtained with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a tape speed control device serving as a base of the present invention in a conventional improvement plan .

FIG. 2 is a diagram showing a speed control signal of the device shown in FIG.

FIG. 3 is a diagram illustrating generation of a speed error signal in the device shown in FIG . 1 ;

FIG. 4 shows a recording head and a reproducing head in a conventional improvement plan.
Is a diagram constitute bets in one member.

FIG. 5 is a configuration diagram of a tape speed control device according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a malfunction in the configuration of FIG. 1;

FIG. 7 is a diagram showing a recording-side speed control signal and a reproduction-side speed control signal in the configuration of FIG. 5;

FIG. 8 is a configuration diagram illustrating a tape speed control device according to another embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional tape speed control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic tape 12 Tape reel 13 Reel motor 14 Recording head 15 Reproduction head 17 Crystal oscillation circuit 18 Recording amplifier circuit 19 Reproduction amplifier circuit 20 Waveform shaping circuit 21 Phase comparison circuit 22 Integrator 23 Motor drive circuit

Claims (2)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for recording / reproducing signals such as audio and video using a magnetic tape as a recording medium,
First及 for recording on the magnetic tape speed control signal for controlling the running speed of the magnetic tape at different frequencies
And beauty second recording head, it at a position spaced by a predetermined distance tape <br/> tape running direction rearward with respect to the respective recording heads
And the magnetic tape is provided by each of the recording heads.
First and second reproducing heads for reproducing the speed control signal recorded on the first reproducing head, and a speed control signal reproduced by the first reproducing head
Difference between speed and the speed control signal recorded by the first recording head
A first phase comparator circuit for detecting a second phase comparator circuit speed control signal the second reproducing head is reproduced and the second recording head for detecting a phase difference between the speed control signal to be recorded, the Addition for adding the outputs of the first and second phase comparison circuits
Device, a reel motor that drives the magnetic tape to travel,
The reel motor is controlled based on the output of the adder.
And a control means for controlling the tape speed. 2. A method for controlling a running speed of a magnetic tape.
Recording head for recording a speed control signal on the magnetic tape
And the above speed control signal at a predetermined distance behind the tape running direction.
A playback head that plays back at a position separated by
The speed control signal reproduced by the raw head and the recording head
Phase comparison circuit that detects the phase difference from the speed control signal to be recorded
And a reel motor for driving the magnetic tape to travel.
And the recording head detected by the phase comparison circuit.
And the phase difference between the speed control signal of
Controlling the reel motor so that
In the preceding stage of the recording head and the reproducing head
Delay the speed control signal to both or one of the subsequent stages.
Tape speed control characterized by having a delay circuit
apparatus.