JP3045334B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order. BACKGROUND OF THE INVENTION Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1 to 3) Function (FIGS. 1 to 3) Example (FIGS. 1 to 3) Effects of the Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and is suitably applied to, for example, a rotary head type digital audio tape recorder.

[0003]

2. Description of the Related Art Conventionally, a rotary head type digital audio tape recorder (DAT) has been used as a magnetic recording / reproducing apparatus for recording audio signals at high density.

In this digital audio tape recorder, input audio data is recorded on a magnetic tape wound around a drum at a predetermined winding angle by using a rotary head mounted on the drum, or recorded on the magnetic tape. The recorded audio data is reproduced by using a rotating head.

In order to correctly reproduce the recorded audio data recorded on the magnetic tape, it is necessary for the rotary head to scan the recording track of the magnetic tape in a helical scan state in a fast tracking state. The recorder uses the so-called ATF (automated
Tracking control is performed by a tracking servo using the technique of atic track following).

In practice, in a digital audio tape recorder, recording tracks having positive and negative azimuth angles are formed alternately in a direction oblique to the running direction of the magnetic tape, and are formed at the lower end and the upper end of the recording track. A predetermined ATF pattern is recorded.

Accordingly, in a digital audio tape recorder, recording tracks having positive and negative azimuth angles are respectively reproduced by rotating heads having a corresponding azimuth angle, and a capstan motor is driven in accordance with a reproduction signal of an ATF pattern obtained as a result. By driving the magnetic tape to variably control the running speed of the magnetic tape, the rotary head can scan the recording track in a helical scan in a just tracking state.

[0008]

In a digital audio tape recorder having such a configuration, for example, when the reproduction is started from a stopped state of the magnetic tape, the rotating head moves on the recording track in a fast tracking state as quickly as possible. It is desirable to control the helical scan.

For this reason, when starting the conventional tracking control, the magnetic tape is controlled to run stably by the running speed servo, and the loop gain of the tracking servo is raised for a predetermined period of time. The rotary head can be controlled to a just tracking state.

However, in such a method of simply increasing the loop gain of the tracking servo, if the rotating head stabilizes in a state where it is on-track on the reverse azimuth recording track, the tracking error itself can be detected. There is a problem that it takes a long time to pull into the just tracking state.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a magnetic recording / reproducing apparatus in which a rotating head quickly scans in a helical manner on a recording track in a just tracking state.

[0012]

According to a first aspect of the present invention, a recording track formed obliquely to a running direction of a magnetic tape 2 is scanned to record and reproduce predetermined information. Magnetic heads 7A and 7B provided on the rotary drum 4, speed error detecting means 9 for detecting a running speed error of the magnetic tape 2, and reproduction for reproducing a recording track formed on the magnetic tape 2 by the magnetic heads 7A and 7B. The magnetic tape 2 is set at a predetermined traveling speed based on the traveling speed error SER detected by the tracking error detecting means 15 for detecting a tracking error obtained from the signal SPB, and the reference speed. When starting the positioning of the magnetic heads 7A and 7B with respect to the recording track, a predetermined offset speed SO is maintained at a reference speed for a predetermined period. A speed servo means 10 to add F,
Tracking servo loop systems 28A and 29 for amplifying the tracking error signal TER with a first loop gain, and amplifying the tracking error signal TER with a second loop gain and integrating the amplification result at the second loop gain. And output the tracking integral servo loop systems 27 and 28B,
29, the magnetic tape 2 is controlled to a predetermined traveling speed based on the tracking error detected by the tracking error detecting means 15, and the magnetic head 7
When the positioning of the recording tracks A and 7B with respect to the recording track is started, a tracking servo means 16 for increasing the first loop gain and the second loop gain is provided.

In the second invention, the tracking servo means 16 increases the first and second loop gains when starting the positioning of the magnetic heads 7A and 7B with respect to the recording track, and after a lapse of a predetermined time (t3). ) After the first loop gain is lowered, the second loop gain is lowered with a delay of a predetermined time (t4).

[0014]

[0015]

When the positioning of the rotary heads 7A and 7B with respect to the recording track is started, a predetermined offset speed SOFF is added to the reference speed for a predetermined period, so that the tracking error signal TER can be reliably generated. By controlling the running speed of the magnetic tape 2 in accordance with this, it is possible to control the rotary heads 7A and 7B to perform helical scan on the recording track in a fast tracking state.

Further, tracking servo means 14, 15,
The tracking servo loop systems 28A, 29 having a first loop gain and the tracking integrating servo loop systems 28B having a second loop gain are represented by 16, 17, 12, 13;
When the positioning of the rotary heads 7A and 7B with respect to the recording track is started, the first and second loop gains are raised, and after a predetermined period of time (t3), the first loop gain is lowered. Thereafter, the second loop gain is lowered with a delay of a predetermined time (t4), so that the rotating heads 7A and 7B can be controlled so as to perform helical scanning in a just tracking state on the recording track more quickly. .

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

In FIG. 1, reference numeral 1 designates an entire structure of a rotary head type digital audio tape recorder as a whole. A magnetic tape 2 is led out from a supply reel (not shown) in a tape cassette and guided by guides 3A and 3B. And wound between a capstan 5 and a pinch roller 6 and taken up on a take-up reel in a tape cassette.

The drum 4 has a pair of rotating heads 7A and 7B.
Is placed on the magnetic tape 2 to perform helical scan, whereby an audio signal can be recorded and reproduced on a recording track formed obliquely to the running direction of the magnetic tape 2.

A frequency generator 8 is attached to the capstan motor 5 A of the capstan 5, and the resulting rotational frequency signal SFG of the capstan 5 is input to the speed error detection circuit 9.

The speed error detecting circuit 9 calculates the running speed of the magnetic tape 2 in accordance with the rotation frequency signal SFG, and compares the running speed obtained as a result with a reference running speed set in advance. A speed error signal SER is generated, and this is
Send to 0.

The speed servo circuit 10 generates a first motor drive signal SDR1 for correcting the input speed error signal SER, and outputs the first motor drive signal SDR1 to the first input terminal a of the first switching circuit 11 and the first addition circuit. The signal is supplied to the motor driver circuit 13 through the control circuit 12.

The motor driver circuit 13 receives the input first
A second motor drive signal SDR2 for driving the capstan motor 5A is generated on the basis of the motor drive signal SDR1 and transmitted to the capstan motor 5A.

Thus, in the case of the digital audio tape recorder 1, a speed servo loop is formed,
By driving the capstan motor 5A based on the speed error signal SER, the magnetic tape 2 can run according to the reference running speed.

In the digital audio tape recorder 1, a tracking servo loop is formed on the basis of the reproduced signal SPB obtained from the rotary heads 7A and 7B, whereby the running speed of the magnetic tape 2 is adjusted according to the tracking error. Has been made to control.

In practice, the reproduction signal SPB obtained from the rotary heads 7A and 7B is input to the tracking error detection circuit 15 through the reproduction amplification circuit 14, so that the tracking error detection circuit 15 corrects the detected tracking error. A tracking error signal TER of 1 is generated and input to the tracking servo circuit 16.

This tracking servo circuit 16 corrects a tracking error on the basis of the input first tracking error signal TER to generate a third motor drive signal SD.
R3 is generated and sent to the addition circuit 12 through the first input terminal a of the second switching circuit 17.

Thus, the motor driver circuit 13 includes:
The first and third motor drive signals SDR1 and SDR3 are added and input, and thus the motor driver circuit 13
Generates a second motor drive signal SDR2 for driving the capstan motor 5A based on the input signal of the first and third motor drive signals SDR1 and SDR3 and sends it to the capstan motor 5A. I do.

By controlling the running speed of the magnetic tape 2 in accordance with the tracking error in this manner, the tracking error is corrected, and as a result, the rotating heads 7A and 7B are moved along the recording track of the magnetic tape 2 in a fast track. It is made to be able to perform helical scan in the king state. The operation timings of the speed servo loop and the tracking servo loop are controlled by a servo loop ON / OFF control circuit 18.

When the digital audio tape recorder 1 is actually stopped, the first and second switching circuits 11 and 17 each have the second input terminal b selected, and the servo loop ON / OFF control circuit 18 Reproduction start signal ST input from a system control circuit (not shown)
First and second switching signals SW1 and SW2
Occurs.

As a result, the first and second switching circuits 11 and 17 are sequentially switched to the first input terminal a, and a speed servo loop and a tracking servo loop are sequentially formed in response thereto. The playback operation is started in the audio tape recorder 1.

Here, in the case of this embodiment, the detailed circuits of the speed servo loop and the tracking servo loop are actually configured as shown in FIG. 2 in which the same reference numerals are assigned to parts corresponding to those in FIG. In the speed servo loop, a speed error signal SER is input to a second adding circuit 20 and a speed lock detecting circuit 21.

The second addition circuit 20 has an offset speed signal S generated by an offset bias generation circuit 22.
OFF is input through the first input terminal a of the third selection circuit 23. As a result, the second speed error signal SER1 corresponding to the selection of the third selection circuit 23 is input to the speed servo circuit 10.

The speed lock detecting circuit 21 detects whether or not the speed servo loop has locked according to the input speed error signal SER. The detection result is used as a speed lock signal SLK and the reproduction start signal SLK is detected.
Together with T, it is input to the servo loop ON / OFF control circuit 18 and the gain control circuit 25 of the tracking servo loop.

On the other hand, in the tracking servo loop, the first tracking error signal TER is input to the tracking servo circuit 16 and the error detection circuit 26
Has been entered.

The error detection circuit 26 is connected to the first input
Is detected according to the tracking error signal TER, and the detection result is used as a tracking lock signal TLK together with the reproduction start signal ST and the gain control circuit 25 and the offset control of the speed servo loop. It is input to the circuit 24.

In this embodiment, the tracking servo circuit 16 is composed of a normal tracking servo loop system and a tracking integral servo loop system including an integration processing circuit 27, as shown by the broken line in FIG. .

That is, the input first tracking error signal TER is input to the first amplifier circuit 28A as a normal tracking servo loop system and the second amplifier circuit 28B as a tracking integral servo loop system. I have.

The first amplifier circuit 28A amplifies the input first tracking error signal TER with a first loop gain, and amplifies the amplified signal with the second tracking error signal TE.
It is input to the third adder circuit 29 as R1.

The second amplifying circuit 28B amplifies the input first tracking error signal TER with the second loop gain and then integrates the amplified signal with the integration processing circuit 27.
To the third adding circuit 29 as the tracking error signal TER2.

The third adding circuit 29 adds the input second and third tracking error signals TER1 and TER2, and outputs the addition result to the third motor drive signal SDR3.
Is sent out.

Here, the first and second loop gains of the first and second amplifier circuits 28A and 28B correspond to the first and second gain switching signals SG1 and SG2 input from the gain control circuit 25, respectively. Thus, the switching can be controlled.

In the above configuration, as shown in FIG.
The reproduction start signal ST (FIG. 3
When the pulse of (A)) occurs, the servo loop is turned ON / O.
The FF control circuit 18 detects this and detects the first switching signal SW
1 (FIG. 3B), thereby switching the first switching circuit 11 to the first input terminal a. At this time, the offset control circuit 24 also detects the pulse of the reproduction start signal ST and raises the third switching signal SW3 (FIG. 3 (C)), thereby switching the third switching circuit 23 to the first input terminal a. Switch to.

In this way, in the digital audio tape recorder 1, a speed servo loop is formed at the timing when the reproducing operation is started, and the magnetic tape 2 is driven at a running speed obtained by adding the offset speed to the reference speed.

In this state, when the running speed of the magnetic tape 2 locks to the speed obtained by adding the offset speed to the reference speed at the timing of time t2, the speed lock detecting circuit 21 detects this and generates the speed lock signal SLK. Occur.

Servo loop ON / OFF control circuit 18
Raises a second switching signal SW2 (FIG. 3D) in response to the speed lock signal SLK, switches the second switching circuit 17 to the first input terminal a, and forms a tracking servo loop. . In addition to this, the second switching signal SW2
Is also supplied to the integration processing circuit 27 of the tracking servo circuit 16, whereby the integration processing circuit 27 is reset.

Actually, in such a state, the magnetic tape 2
Are traveling at a speed obtained by adding the offset speed to the reference speed, so that the rotating heads 7A and 7B
Helical scan while slipping over the recording track. Therefore, the tracking error detecting circuit 15 can always detect a tracking error immediately.

In this state, since the offset speed is added to the running speed of the magnetic tape 2 in the tracking servo loop, it is necessary to increase the loop gain of the tracking servo when trying to pull in the just tracking state.

Therefore, the gain control circuit 25 raises the first and second gain switching signals SG1 and SG2 (FIGS. 3E and 3F) in response to the speed lock signal SLK, and the first and second gain switching signals SG1 and SG2. The first and second loop gains of the amplifier circuits 28A and 28B are increased, thus making it easier for the tracking servo loop to be pulled into the just tracking state.

In the state where the loop gain is increased in this manner, in the tracking servo loop, the first loop gain of the ordinary tracking servo system works dominantly, and the tracking integral servo having the second loop gain is used. Not much is accumulated in the integral term of the system.

In this state, when the rotary heads 7A and 7B run on the recording track of the magnetic tape 2 in a fast tracking state at the timing of time t3, the error detecting circuit 26 detects this and performs tracking. A lock signal TLK is generated.

The offset control circuit 24 causes the third switching signal SW3 to fall in response to the tracking clock signal TLK, whereby the third selection circuit 23 causes the first input terminal a to be turned off.
To the second input terminal b, thereby forming a speed servo loop for running the magnetic tape 2 at a reference speed to which no offset speed is added.

At this time, the gain control circuit 25 simultaneously lowers the first gain switching signal SG1, thereby returning the raised loop gain of the first amplifier circuit 28A to a normal value. At this time, the second amplifier circuit 28B
It is conceivable that the loop gain is returned to the normal value, but in this case, the tracking in the locked state may come off.

For this reason, in this embodiment, the first
After returning the loop gain of the amplifier circuit 28A to the normal value,
The loop gain of the second amplifying circuit 28B is kept raised, and the tracking error signal TER is accumulated in the integration term of the tracking integration servo system, that is, the integration processing circuit 27. The second gain switching signal SG2 is caused to fall, thereby returning the raised loop gain of the second amplifier circuit 28B to the normal value.

As a result, the offset speed and the first and second loop gains can be returned to the normal state without removing the tracking servo once pulled into the locked state. After that, the speed servo and the tracking servo can be returned to the normal state. , The reproduction of the magnetic tape 2 is continued.

According to the above configuration, a predetermined offset speed is added to the reference speed in the speed servo for a predetermined period from the start of reproduction, so that a tracking error signal can be reliably generated. Thus, the digital audio tape recorder 1 can be realized in which the rotating heads 7A and 7B can quickly scan the recording track of the magnetic tape 2 in a helical scan with the tracking servo.

Further, according to the above-described configuration, the period in which the offset speed is applied and the period in which the first loop gain of the tracking group system and the second loop gain of the tracking integration loop system are raised are each controlled by a time difference. As a result, the digital audio tape recorder 1 can be realized in which the rotating heads 7A and 7B can be helically scanned on the recording track of the magnetic tape 2 in a fast tracking state by the tracking servo.

In the above-described embodiment, the case where the present invention is applied to a digital audio tape recorder has been described. However, the present invention is not limited to this.
(Video tape recorder) It is suitable for wide application to a magnetic recording / reproducing apparatus for helically scanning a magnetic tape with a constant rotation head.

[0059]

As described above, according to the present invention, when the positioning of the magnetic head with respect to the recording track is started, a predetermined offset speed is added to the reference speed for a predetermined period, so that a tracking error signal can be obtained. Can be generated reliably, the running speed of the magnetic tape is controlled in accordance with the tracking error signal, and the magnetic head can be controlled so that the magnetic head quickly scans the recording track in a helical scan state in the fast tracking state. A recording / reproducing device can be realized.

Further, the tracking servo means is constituted by a tracking servo loop system having a first loop gain and a tracking integral servo loop system having a second loop gain so as to start positioning the magnetic head with respect to the recording track. By increasing the first and second loop gains, lowering the first loop gain after a predetermined period has elapsed, and then lowering the second loop gain with a delay of a predetermined time, the magnetic field can be further rapidly increased. It is possible to realize a magnetic recording / reproducing apparatus capable of controlling a head to perform a helical scan in a just tracking state on a recording track.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a digital audio tape recorder according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of the speed servo system and the tracking servo system.

FIG. 3 is a timing chart for explaining the operation of the speed servo system and the tracking servo system.

[Explanation of symbols]

1 ... Digital audio tape recorder, 2 ... Magnetic tape, 4 ... Drum, 5 ... Capstan, 6 ...
Pinch rollers, 7A, 7B: rotating head, 9: speed error detection circuit, 10: speed servo circuit, 1
1, 17, 23 ... switching circuit, 12, 20 ... addition circuit, 13 ... motor driver circuit, 15 ... tracking error detection circuit, 16 ... tracking servo circuit,
18 ... Servo loop ON / OFF control circuit.

Claims (2)

(57) [Claims] 1. A magnetic tape formed obliquely to a running direction of a magnetic tape.
Scans the recorded recording track and records and reproduces the specified information.
A magnetic head provided on the rotating drum and a speed error for detecting a running speed error of the magnetic tape.
Detecting means for connecting the recording track formed on the magnetic tape to the magnetic tape;
Tracking error obtained from the playback signal played back with the edge
And a traveling speed error detected by the speed error detecting means.
The magnetic tape based on the error and the reference speed.
Control the line speed and record the magnetic head
When starting positioning for the track, the above
Speed servo means for adding a predetermined offset speed to the quasi-speed
If, amplifying the tracking error signal in the first loop gain
Tracking servo loop system and the tracking
The error signal is amplified by the second loop gain and
Tras for integrating and outputting the amplification result with loop gain of 2
Having a king integral servo loop system and the tracking
Tracking error detected by error detection means
Controls the magnetic tape to a predetermined traveling speed based on
With the magnetic head relative to the recording track.
When starting the positioning, the first loop gain and the second
And a tracking servo means for increasing the loop gain of the magnetic recording / reproducing apparatus. 2. The tracking servo means according to claim 1 , wherein
Start positioning the head relative to the recording track
When the first and second loop gains are increased,
After a lapse of time, the first loop gain is lowered and then delayed for a predetermined time.
Is in 請characterized by lowering said second loop gain
The magnetic recording / reproducing apparatus according to claim 1.