JPH06119684A - Reproducing device - Google Patents

Abstract

PURPOSE:To uniformalize the time required to obtain a reproduced picture after entrance to the correct tracking state at the time of start or the like. CONSTITUTION:The signal reproduced from a magnetic tape 1 by a head 2 is supplied to an ATF circuit 4 and a low pass filter 5 through a regenerative amplifier 3. The ATP (tracking) error signal from the ATF circuit 4 is supplied to a microcomputer 7 through an A/D conversion circuit 6. A signal corresponding to the envelope of the RF (reproduced) signal from the low pass filter 5 is supplied to the microcomputer 7 through an A/D conversion circuit 8. Further, the signal from an PG detecting sensor 10 of a capstan 9 which transports the magnetic tape 1 is supplied to the microcomputer 7 through an FG amplifier 11. The control signal calculated by the microcomputer 7 is supplied to a drive circuit 12 to control driving of the capstan 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a digital VT.
The present invention relates to a reproducing device suitable for use in R.

[0002]

2. Description of the Related Art In a VTR, for example, the recording density has been increased, and the narrowing of the recording track on the tape has been promoted as a means for that. Particularly, in a digital VTR for recording / reproducing a signal as digital data, since the recording is made multi-track, the width is further narrowed.

Tracking control of such a narrowed recording track is no longer possible by a method using a conventional CTL track, for example. Therefore, the applicant of the present application has previously proposed a tracking control method for such a narrowed recording track (Japanese Patent Application No.
114802).

That is, FIG. 6 shows a recording pattern used in the prior application. In this pattern, a pilot signal (frequency f ₂ ) for tracking control is recorded for every four tracks, and a detection signal (frequency f ₁ ) is recorded on the tracks on both sides thereof. Then, during normal reproduction for this recording pattern, tracking control is performed by detecting crosstalk of the pilot signal (f ₂ ) reproduced by the head reproducing track A on the inlet side and the head reproducing track B on the outlet side. To be done.

However, when the tracking control is performed using such a recording pattern, if the relationship between the head and the recording track, which have different azimuth angles alternately at the time of start-up, is just opposite, the above-mentioned situation occurs. It is not possible to detect the reproduction of the signal for performing the tracking control, and it takes a long time until the correct tracking state is achieved. Therefore, the time until the reproduced image is obtained in the correct tracking state at the time of start-up becomes non-uniform, which may cause a problem in terms of commercial value. This application is made in view of such a point.

[0006]

The problem to be solved is that the time until the reproduced image is obtained in the correct tracking state at the time of start-up is not uniform.

[0007]

According to a first means of the present invention, the tape transfer speed at start-up is controlled to be different from the standard to perform speed control, and a tracking error signal (ATF circuit 4) in the reproduced signal at that time is controlled. On the basis of the above, the reproducing apparatus is characterized in that the tape transfer speed is standardized at the timing of the predetermined position to perform tracking control.

According to the second means of the present invention, the tape transfer speed at the time of starting is controlled to be different from the standard, and the speed is controlled, and the timing of the predetermined position is based on the envelope (low-pass filter 5) of the reproduced signal at that time. In the reproducing apparatus, the tape transfer speed is standardized to perform the tracking control.

According to a third means of the present invention, one field is divided into a plurality of tracks for recording, and a recording medium having a pilot signal recorded therein is mounted on each of the four tracks to reproduce the pilot signal. In the reproducing apparatus configured to perform tracking control according to the first means or the second means, the reproducing apparatus is characterized in that the tracking control described in the first means or the second means is performed.

[0010]

According to this, the time until the reproduced image is obtained in the correct tracking state at the time of starting can be made uniform.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of the main part. In this figure,
A signal reproduced by the head 2 from the magnetic tape 1 is supplied to the ATF circuit 4 and the low-pass filter 5 through the reproduction amplifier 3. The ATF (tracking) error signal from the ATF circuit 4 is supplied to the microcomputer 7 through the A / D conversion circuit 6. Also low-pass filter 5
A signal corresponding to the envelope of the RF (reproduction) signal from is supplied to the microcomputer 7 through the A / D conversion circuit 8.

Reference numeral 9 denotes a capstan for transferring the magnetic tape 1. FG detection sensor 1 of this capstan 9
The signal from 0 is supplied to the microcomputer 7 through the FG amplifier 11. Then, the control signal calculated by the microcomputer 7 is supplied to the drive circuit 12 to control the drive of the capstan 9.

Further, FIG. 2 is a functional block diagram for explaining the processing in the microcomputer 7. In this figure, the FG signal from the above-mentioned FG amplifier 11 is supplied to the FG interval measuring unit 70, and the measured FG interval is supplied to the capstan speed converting unit 71. The signal from the conversion unit 71 is supplied to the subtraction unit 72, the speed target value 73 is subtracted, and the speed error signal is calculated. This error signal is sent to the gain adjusting section 7 through the servo calculating section 74.
5 is supplied.

Further, the ATF error signal from the A / D conversion circuit 6 is supplied to the subtraction section 76, and the ATF error target value 77 is supplied.
Is subtracted and the tracking error signal is calculated. This error signal is supplied to the gain adjusting section 79 through the servo calculating section 78. And these gain adjusting units 75,
The velocity error signal from 79 and the tracking error signal are added by the adder 80 to form a control output signal.

Further, the control output signal is the PWM circuit 8
1. Motor driver 83 through low pass filter 82
And a capstan motor (not shown) is controlled. The PWM circuit 81 and the low-pass filter 8
2. A part of the circuit such as the motor driver 83 may be provided in the chip as a peripheral circuit of the microcomputer 7.

Then, in this apparatus, the processing by the microcomputer 7 is performed as shown in the flowchart of FIG. In this figure, this flow chart is executed in the FG interrupt process with the capstan activated.

That is, the presence or absence of the ATF servo command is determined in step [1], and when there is no command at the time of start-up, the speed reference (target value) is set to, for example, 0.8 times speed in step [2]. Next, in step [3], speed servo processing is performed. Further, in step [4], it is determined whether or not the speed error range is entered.

If it is within the range in step [4], it is judged in step [5] whether or not the ATF error is sampled. Furthermore, when sampling is performed in this step [5], 0 described later in step [6] is used.
It is determined whether the cross detection flag is "1". And 0
When the cross detection flag is "0", it is set to 1 in step [7].
A comparison is made with the data before the sample.

If the value has changed to a positive value in step [7], the absolute values are compared in step [8]. If the absolute value comparison is positive here, step

The counter is incremented in [9], and the step [1
0], the 0 cross detection flag is set to "1". Further, in step [11], it is judged whether or not the count value of the counter is "2".

When the count value is "2" in step [11], the value two samples before is subtracted from the current sample value in step [12], and the gain calculation described later is performed in step [13]. Then, in step [14], the reference is calculated at the time of track shift described later. Further, in step [15], it is judged whether or not the count value of the counter is an arbitrary value "A". If "A", the ATF servo command is issued in step [16] and the operation is terminated.

When the value is out of the range in step [4], the value is changed to negative in step [7], and the absolute value comparison is negative in step [8], step [17] Then, the count value of the counter is set to "0" and the operation is ended. Also step [5]
If the sampling is not performed at, the operation is finished as it is.

Further, when the 0-cross detection flag is "1" in step [6], the step is continued as it is.

Go to [9]. If the count value is not "2" in step [11], the process directly proceeds to step [15]. If the count value of the counter is not "A" in step [15], the operation is terminated as it is.

On the other hand, when the ATF servo command is issued in the above step [16], the ATF servo command is issued in step [1].
It is determined that there is a TF servo command. In this case, the speed reference (target value) is set to 1 × speed in step [18]. Next, in step [19], speed servo processing is performed. Further, in step [20], the speed servo gain is adjusted.

Further, in step [21], it is judged whether or not ATF error sampling has been performed. When sampling is performed in step [21], the ATF servo processing is performed in step [22]. Also, in step [23], the ATF servo gain is adjusted.

Then, in step [24], the speed servo and A
The value of TF servo is added, and PWM is performed in step [25].
To be converted. This PWM converted signal is used in step [2
6] and the operation is terminated. In addition, step [2
When sampling is not performed in 1], the previous value is PWM-converted as it is in step [25].

Therefore, in this apparatus, the tape transfer speed at start-up is first 0.8 as shown in FIG. 4A.
To be doubled. At this time, the envelope of the RF signal becomes as shown in B of the same figure, and the ATF error signal becomes as shown in C of the same figure. Here, if the tape transfer speed is kept at 0.8 times, the tracking change is
As shown in Fig. 10, the change is repeated every time 10 tracks during reproduction, and the RF signal envelope and AT
The F error signal is as shown by the broken line in the figure.

On the other hand, when the speed servo stabilizes at 0.8 times speed at time t ₁ in the figure, the next ATF error signal becomes 0.
The time point t ₂ of the cross detection flag is detected. The counter starts incrementing from here, and the count value is "A".
The target value of the speed servo is made 1 × speed at the time t ₃ at which The time point t _{4 of the} next zero cross of the ATF error signal
Thus, the speed servo and the tracking servo of 1 × speed are executed.

That is, in this apparatus, tracking is correctly performed at time t ₄ when the ATF error signal is 0-crossed, and by starting velocity servo and tracking servo at this time t ₄ , tracking servo without malfunction is performed. be able to. The above-mentioned count value “A” is arbitrarily set according to the time difference between the time points t ₃ and t ₄ of the target device.

Thus, according to the above-mentioned apparatus, it is possible to make the time until the reproduced image is obtained in the correct tracking state at the time of starting.

In the above apparatus, the tape transfer speed at the time of startup is not limited to 0.8 times speed. Here, the closer the speed ratio is to 1x speed, the more accurate the waveform of the ATF error signal or the like becomes. However, for example, in the case of 0.9x speed, the above tracking change is repeated every time 20 tracks during reproduction. This changes, and the time required to detect the 0 cross is doubled. On the other hand, by analyzing the waveform of the ATF error signal or the like with the microcomputer 7, there is a possibility that the waveform can be detected even at about 0.6 × speed.

Further, in the above apparatus, the time t ₂ at which the tracking is correctly performed is detected even when the 0 cross of the ATF error signal is not detected, but the time when the envelope of the RF signal reaches the maximum value is detected. You may do it.

Further, by subtracting the value two samples before from the current sample value in step [12] of the above-mentioned flow chart, for example, Δ as shown on the left side of FIG.
The value of E'is obtained. On the other hand, if the slope of ΔE as shown on the right side of the figure is ideal, then K = kΔE / ΔE ′ (k is a fixed gain constant) is calculated in the above step [13], and this value is By using, for example, adjusting the gain of the gain adjusting unit 79, it is possible to absorb variations in the gain of the servo loop.

Further, when the tape is transported at a speed of 0.8, for example, the tracking shifts by (1-8 / 10 = 0.2) tracks between two samples of the ATF error signal. Since the change in the error at that time is ΔE ′, the error voltage when the track is shifted by X% is ΔE ′ × (1 track / 0.2 track) × (X% / 1
00%), and this value is calculated in the above-mentioned step [14], and using this value, tracking servo can be performed in an arbitrary track-shifted state.

[0034]

As described above, according to the present invention, it becomes possible to make the time until the reproduced image is obtained in the correct tracking state at the time of starting.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of a main part of a reproducing device according to the present invention.

FIG. 2 is a diagram for explaining the explanation.

FIG. 3 is a flow chart diagram for explaining that.

FIG. 4 is a time chart diagram for the explanation.

FIG. 5 is a diagram for explaining that.

FIG. 6 is a diagram for explaining a tracking control method for a narrowed recording track previously proposed by the applicant of the present application.

[Explanation of symbols]

 1 magnetic tape 2 head 3 reproduction amplifier 4 ATF circuit 5 low-pass filter 6, 8 A / D conversion circuit 7 microcomputer 9 capstan for transferring magnetic tape 1 10 FG detection sensor 11 FG amplifier 12 drive circuit

Claims (3)

[Claims] 1. A tape transfer speed at start-up is controlled to be different from the standard to perform speed control, and the tape transfer speed is set to the standard at the timing of a predetermined position based on a tracking error signal in a reproduction signal at that time. A reproducing device characterized in that tracking control is performed by using the following. 2. A tape transfer speed at the time of start-up is controlled to be different from the standard to perform speed control, and the tape transfer speed is standardized at the timing of the predetermined position based on the envelope of the reproduction signal at that time to perform tracking control. A reproducing apparatus characterized by performing the following. 3. A recording medium in which one field is divided into a plurality of tracks and recorded, and a pilot signal is recorded in one track of every four tracks, the pilot signal is reproduced to perform tracking control. In the reproducing apparatus, the tracking control according to claim 1 or 2 is performed.