JPH0574137B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an automatic tracking control device in a rotating head type magnetic recording/reproducing device.

[Prior art]

A magnetic tape used in a magnetic recording/reproducing device such as a digital audio tape recorder has a track pattern as shown in FIG. The track pattern of this magnetic tape will be explained.

That is, the symbols T1 to T5 are respective tracks on the magnetic tape. HD indicates the tracing direction of the rotating head that traces each track, and TD indicates the running direction of the magnetic tape. Each of the tracks T1 to T5 includes a first control signal recording area ATF1 for automatic tracking control along the tracing direction HD of the rotating head, and a video signal recording area for even or odd frames.
VS and the second control signal recording area ATF2 are recorded in this order. In each control signal recording area ATF1, ATF2, there is a signal indicated by f1.
A 130.67kHz pilot signal (a signal used to detect the amount of tracking deviation from the main track of the rotating head), a 522.67kHz first synchronization signal indicated by f2, and a 784.00kHz second synchronization signal indicated by f3, A 1.568MHz erase signal indicated by f4 is recorded. In addition, the video signal recording area
A in VS indicates an area traced by a rotating head of positive azimuth, and B indicates an area traced by a rotating head of negative azimuth.

In a magnetic tape having such a track pattern, assuming that the rotary head is currently tracing the track T3, the respective second synchronization signals of both control signal storage areas ATF1 and ATF2 on that track, that is, the scanning track T3 f
3 is reproduced by the rotating head, and at the same time as this reproduction, the pilot signal f1 is generated in the respective control signal recording areas ATF1 and ATF2 in the tracks T2 and T4 on both sides adjacent to the scanning track T3.
are played respectively.

In accordance with the amount of tracking deviation of the rotating head from the scanning track T3, in the conventional magnetic recording/reproducing apparatus, the sample and hold pulse obtained in conjunction with the detection timing of the second synchronizing signal f3 is detected by the rotating head. Pilot signal f in each control signal recording area ATF1, ATF2 on both sides
1 The mutual level difference is used as a tracking error signal to sample and hold until the next sample and hold pulse is given in the sample and hold circuit, and the rotation speed of the capstan motor is controlled using the sample and hold value. , the tracking of the rotating head was corrected in the correct direction.

However, in the digital audio tape recorder using magnetic tape as described above, the output intervals of the sample and hold pulses may not be the same, so an offset occurs between the trace of the rotating head and the scanning track. ,
There was a problem that automatic tracking control of the rotating head was difficult to perform.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to enable automatic tracking control of a rotating head to be easily applied even if the output intervals of sample-and-hold pulses are not the same.

[Structure of the invention]

To achieve this object, the present invention generates a tracking deviation signal indicating the amount of tracking deviation of a rotating head from a scanning track in response to a sample-and-hold pulse applied in conjunction with a synchronization signal recorded on the scanning track. automatic tracking control in a rotary head type magnetic recording/reproducing device, comprising: a sample and hold circuit that performs sampling and holding; and a control means that controls the tracking speed of a rotary head according to the gain of a tracking deviation signal of the sample and hold circuit. The circuit includes a measurement circuit that measures the pulse interval of the sample-and-hold pulse and outputs a measurement signal indicative of the measured value, and a measurement circuit that is provided between the sample-and-hold circuit and the control means, The present invention is characterized by comprising a gain switching circuit that switches the gain of the tracking deviation signal in response to the measurement signal and outputs the same to the control means.

According to this configuration, the sample and
A measurement signal indicating the measurement result of the pulse interval of the hold pulse is output. Then, in response to the measurement signal, the gain switching circuit switches the gain of the tracking deviation signal sampled and held in the sample and hold circuit, and outputs it to the control means for controlling the tracking speed of the rotary head.

Therefore, according to the present invention, it is possible to eliminate tracking deviation of the rotary head and perform correct tracking even when the pulse intervals of the sample-and-hold pulses are not the same.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of a rotary head type magnetic recording/reproducing device (digital audio tape recorder) including an automatic tracking control device according to an embodiment of the present invention. In Figure 1, 1 is the third
A magnetic tape having the track pattern shown in the figure, 2 a rotary head that traces the magnetic tape 1 in the direction of the arrow HD in FIG. 3, 3 a rotary head 2;
4 is a low-pass filter (LPF) that detects and outputs the pilot signal f1 from the reproduced signal from the rotating head 2 amplified by the head amplifier 3; 5 is a low-pass filter (LPF) that detects the output of the low-pass filter 4; A detection circuit 6 is a first sample/hold circuit that samples and holds the output of the detection circuit 5 in response to the first sample/hold pulse p1.
A hold circuit, 7 is a subtraction circuit that subtracts the output of the detection circuit 5 and the output of the first sample and hold circuit 6, and 8 is a subtraction circuit that samples and holds the output of the subtraction circuit 7 in response to the second sample and hold pulse p2. It is a 2 sample hold circuit.

9 and 10 are the first and second synchronization signals f2 and f from the reproduction signals from the rotary head 2, respectively.
3, and 11 detects and outputs the first sample and hold pulse p1 in response to the synchronization signal from both the synchronization signal detection circuits 9 and 10, respectively. A sample-and-hold pulse generating circuit 12 delays the first sample-and-hold pulse p1 by the time of two blocks shown in FIG. A delay circuit 13 outputs to the hold circuit 8 and is a drive circuit that drives the capstan motor 14 in response to the tracking deviation signal. The drive circuit 13 and the capstan motor 14 constitute a control means for controlling the tracking speed of the rotary head 2.

In such a configuration, this embodiment is characterized by a circuit configuration 15 surrounded by a broken line in the figure. That is, this embodiment includes a pulse interval measuring circuit 16 that measures the pulse interval of the second sample and hold pulse p2 given from the delay circuit 12 and outputs a measurement signal indicating the measured value, and a second sample and hold circuit. 8 and the drive circuit 13, a gain switching circuit 17 that switches the gain of the tracking deviation signal in response to the measurement signal from the pulse interval measurement circuit 16 and outputs it to the drive circuit 13.
It is equipped with

Next, the operation will be explained with reference to FIG. Second
Figure a shows a rotating head 2 amplified by a head amplifier 3.
2b is the second sample-and-hold pulse n2 output from the delay circuit 12, and FIG. 2c is the output of the second sample-and-hold circuit 8 (tracking deviation signal before gain switching). FIG. 2d shows the output of the gain switching circuit 17 (tracking deviation signal after gain switching). Further, in this explanation, it is assumed that the rotary head 2 traces the track T3 (main track) in FIG. 3.

First, when the rotating head 2 traces the scanning track T3 of the magnetic tape 1, a reproduced signal as shown in FIG. The signals are respectively applied to the second synchronization signal detection circuit 10. In this case, since the head width of the rotary head 2 is wider than the track width, the reproduced signal includes not only the reproduced signal in each recording area portion on the scanning track T3 side, but also the reproduced signals from the tracks T2 on both sides thereof.
Contains reproduction signals in each recording area portion of T4.

Then, the low-pass filter 4 outputs the pilot signal f of each of the tracks T2 and T4 on both sides.
1 is detected and output. In this case, in terms of time, the pilot signal f1 (first pilot signal f1) on track T2 is detected and outputted first, and then the pilot signal f1 (second pilot signal f1) on track T4 is detected and outputted.

The second synchronization signal f3 is detected and output by the second synchronization signal detection circuit 10, and this detection output is given to the sample-and-hold pulse generation circuit 11.
The sample-and-hold pulse generating circuit 11 generates and outputs the first sample-and-hold pulse p1 in response to its detection output, and the timing of the generation and output is such that the first pilot signal f1 is sent to the first sample-and-hold circuit 6. It is synchronized with the input timing. Therefore, the first sample and hold circuit 6 samples and holds the first pilot signal f1. Next, when the second pilot signal f1 is detected and output, the subtraction circuit 7 subtracts the first pilot signal f1 in the first sample and hold circuit 6 and the second pilot signal f1 detected by the detection circuit 5. . In this case, if the rotary head 2 is not out of tracking, the levels of the first and second pilot signals f1 are the same, so the subtraction output of the subtracting circuit 7 becomes zero, and the tracking of the rotary head 2 is not out of alignment. If so, the subtracted output value changes in accordance with the amount of tracking deviation. This subtracted output value is given to the second sample and hold circuit 8 as a tracking deviation signal.

On the other hand, the sample/hold pulse generation circuit 11
The first sample-and-hold pulse p1 from the second sample-and-hold pulse p1 is delayed by two blocks in the delay circuit 12 and inputted to the second sample-and-hold circuit 8 as a second sample-and-hold pulse p2. The second sample and hold circuit 8 samples and holds the tracking deviation signal inputted from the subtraction circuit 7 in response to the second sample and hold pulse p2. The sampled and held tracking deviation signal is shown in FIG. 2c.

Here, in FIG. 2b, the rotating head 2 is
First control signal recording area ATF of scanning track T3
The pulse interval position of the second sample-and-hold pulse p2 when tracing 1 is at time t1, and the second sample-and-hold pulse p2 when tracing the second control signal recording area ATF2 is at time t1.
The pulse interval position of is at time t2. Also, when the main track of the rotary head 2 becomes the next track T4, and the rotary head 2
The second sample/hold pulse p2 when tracing the first control signal recording area ATF1 of No. 4
The pulse interval position is at time t3, and when tracing the second control signal recording area ATF2, the second pulse interval position is at time t3.
The pulse interval position of the sample-and-hold pulse p2 is at time t4. Hereinafter, since the process is the same after time t4, the explanation thereof will be omitted.

Therefore, at time t1, the second sample
The first tracking deviation signal A shown in FIG. 2c, sampled and held by the second sample and hold circuit 8 in response to the hold pulse p2, is held until the next time t2. The second tracking deviation signal B sampled and held by the second sample and hold circuit 8 in response to the first sample and hold pulse p2 at time t2 is
Holds up to 3. Therefore, from time t1 to
The pulse interval W1 at t2 is different from the pulse interval W2 between times t2 and t3. The same applies hereafter.

The pulse interval measuring circuit 15 measures the pulse intervals W1, W2, W3, . Output to.

The gain switching circuit 17 controls each pulse interval W1, W
When the measurement signals corresponding to 2,... are given from the pulse interval measuring circuit 16, the tracking deviation signals A, B, C,
Switch the gain of... That is, when a measurement signal corresponding to a short pulse interval W1 is given, the gain is small, for example "1", and when a measurement signal corresponding to a long pulse interval W2 is given, the gain is large, for example "T1/T2". ”.

Therefore, in the case of the pulse interval W1, the tracking deviation signal A with a gain of A is given to the drive circuit 13, and in the case of the pulse interval W2, the tracking deviation signal A is given to the drive circuit 13.
A tracking deviation signal B with a gain of B' [=B·(T1/T2)] is applied to the signal. By this,
The capstan motor 14 servo-controls the rotary head 2 so that there is no tracking deviation even if the pulse intervals are different.

Note that this embodiment can be similarly applied to a long play double scan type magnetic recording/reproducing device. In this case, the rotational speed of the drum containing the rotary head 2 is the same as that for normal playback, but the running speed of the magnetic tape is half that of normal playback. As shown by the broken line, for example, only a small reproduced signal can be obtained from time t5 to t8, so especially from time t4 to t8, only a small reproduced signal can be obtained.
The pulse interval at t9 becomes longer. Therefore, this embodiment is particularly effective for such a double scan type device.

〔effect〕

As is clear from the above description, according to the present invention, it is possible to eliminate tracking deviation of the rotary head and perform correct tracking even when the pulse intervals of the sample-and-hold pulses are not the same.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a magnetic recording/reproducing device according to an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation, and FIG. 3 is a track pattern of a magnetic tape used in the magnetic recording/reproducing device. It is a diagram. 1... Magnetic tape, 2... Rotating head, 4...
Low-pass filter, 6...First sample/hold circuit, 7...Subtraction circuit, 8...Second sample/hold circuit
Hold circuit, 9, 10... synchronous signal detection circuit,
11...Sample/hold pulse generation circuit, 1
2...Delay circuit, 13...Drive circuit, 16...Pulse interval measurement circuit, 17...Gain switching circuit.

Claims (1)

[Scope of Claims] 1. A sample for sampling and holding a tracking deviation signal indicating the amount of tracking deviation of the rotating head from the scanning track in response to a sample-hold given in relation to a synchronization signal recorded on the scanning track. - An automatic tracking control device for a rotary head type magnetic recording/reproducing device, which includes a hold circuit and a control means for controlling the tracking speed of the rotary head according to the gain of the tracking deviation signal of the sample and hold circuit, a measurement circuit that measures the pulse interval of the pulses and outputs a measurement signal indicative of the measured quantity; and a measurement circuit that is provided between the sample-and-hold circuit and the control means and that responds to the measurement signal from the measurement circuit. An automatic tracking control device for a rotary head type magnetic recording/reproducing device, comprising a gain switching circuit for switching the gain of the tracking deviation signal and outputting the same to the control means.