KR0167338B1 - Magnetic recording/reproducing device - Google Patents

Abstract

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Description

Magnetic recording and playback device

1 is a block diagram illustrating one embodiment of the invention.

2 is a flow chart illustrating the operation of one embodiment.

3 is an explanatory diagram showing a state of tracking.

4 is an explanatory diagram showing tracking and reproduction RF signal levels.

5 and 6 are explanatory diagrams showing the relationship between the tracking error and the level of the reproduced RF signal, respectively.

* Explanation of symbols for main parts of the drawings

1,10 magnetic head 6: capstan

7: motor 9: driver amplifier

13 comparator 20 digital servo control circuit

[Overview of invention]

The present invention relates to a magnetic recording and reproducing apparatus, and more particularly, to a helical scanning magnetic recording and reproducing apparatus.

The present invention provides a helical scanning magnetic recording and reproducing apparatus, comprising: a signal level discriminating means for determining the increase and decrease of the level of a reproduction high frequency signal output from a rotating magnetic head, and a traveling speed of the magnetic tape based on the discriminating output of the signal level discriminating means; And means for controlling the gain and gain correction means for correcting the nonlinearity of the level change of the reproduction high frequency signal with respect to the tracking error, thereby enabling stable tracking control.

[Prior art]

The tracking control method in the helical scan type VTR includes a CTL method using a CTL signal or an ATF method using a pilot signal of four frequencies. However, in either case, the circuit configuration is complicated, which leads to a cost increase, and in the CTL method, the improvement in recording density is hindered.

In order to solve such a problem, a tracking control method that requires recording of a signal for tracking control, for example, a tracking control method based on a reproduced RF signal, has been proposed. One of these tracking control methods is a so-called dynamic tracking method. However, even in the dynamic tracking method, a voltage-mechanical converter and a driving circuit such as a dark bimorph, for example, are required, and the configuration is complicated, resulting in a cost increase.

Therefore, in the specification of Japanese Patent Application No. 63-241366, the present applicant applies a magnetic recording and reproducing apparatus which performs tracking control by using information on the level of the disputed RF signal (hereinafter referred to as the reproduction Rf signal level) and the acceleration / deceleration state of the magnetic tape. Is proposing.

[Problem to Solve Invention]

However, in the tracking control method as described herein, since the consideration of the nonlinear characteristics of the reproduction RF signal level with respect to the tracking error is not made, the saddled tracking control is difficult.

6 shows the nonlinear nature of the regenerative RF signal level for tracking errors. In the figure, when the magnitude of the reproduction RF signal level corresponding to the predetermined tracking error is a gain, the gain becomes large at the point A, and the gain becomes small at the B point.

By the way, in the servo loop, a driver amplifier for servo driving, which is one of the factors defining the gain of the servo system, is provided, but the gain of the driver amplifier may be relatively small at point A because the above-described gain is large. In point B, the above gain is small, so the gain of the driver amplifier must be relatively large.

Therefore, if the gain of the driver amplifier is adjusted to the level of A point, the gain of the servo system is insufficient at point B, so it is off-track. If the level of the point B is adjusted, the gain of the servo system is excessive at the point A. There was a problem that it was difficult to stably perform tracking control due to deterioration of characteristics.

It is therefore an object of the present invention to provide a magnetic recording and reproducing apparatus capable of performing stable tracking control.

[Means for solving the problem]

The present invention provides a signal level discriminating means for discriminating the level of a reproduction high frequency signal outputted from a rotating magnetic head in a magnetic recording and reproducing apparatus in which a recording track inclined on a magnetic tape is scanned with a rotating magnetic head to obtain a reproduction signal. And means for controlling the traveling speed of the magnetic tape based on the discrimination output of the signal level discriminating means, and gain correction means for correcting the nonlinearity of the level change of the reproduction high frequency signal with respect to the tracking error. .

[Action]

The increase and decrease of the level of the reproduction high frequency signal output from the rotating magnetic head is determined, and the traveling speed of the magnetic tape is controlled based on this discrimination output. On the other hand, the degree of tracking error is determined by the level of the reproduction high frequency signal output from the rotating magnetic head.

In the control of the traveling speed of the magnetic tape, the nonlinearity of the level change of the reproduction high frequency signal is corrected, and the gain of the driver amplifier of the servo system is set corresponding to the above-described tracking error.

Based on this, the servo motor is driven and the tracking error is corrected. As a result, stable tracking control becomes possible.

EXAMPLE

EMBODIMENT OF THE INVENTION Hereinafter, one Example of this invention is described with reference to FIGS. This embodiment applies the magnetic recording and reproducing apparatus according to the present invention to a VTR.

In the configuration shown in FIG. 1, the magnetic heads 1, 10 are attached to the rotating drum 2 and driven by a direct-connected motor 3. The motor 3 is attached with a rotating phase pulse generator 4 (so-called PG) and a frequency signal generator 5 (so-called FG).

The traveling speed of the magnetic tape T wound around the rotary drum 2 in a predetermined range is controlled by the capstan 6. The capstan 6 is directly connected to the motor 7 and attached to the FG 8.

In the magnetic heads 1 and 10, a reproducing RF signal is supplied to the envelope detector 12 via the amplifier 11, and the envelope detection is carried out. The detection output EV is one terminal of the comparator 13 and the digital servo control circuit 20. Are each supplied.

The influence of the tracking of the magnetic heads 1 and 10 on the reproduction RF signal level will be described with reference to FIGS. 3 and 4. In addition, the change in the reproduction RF signal level shown in FIG. 4 represents an ideal state and actually has the nonlinear characteristic as shown in FIG.

The width Wh of the magnetic heads 1 and 10 is set equal to the track width Whk, and the relative positions of the magnetic heads 1 and 10 and the tracks are as shown in FIG. Are represented.

(1) A state of partially scanning the upstream track Tku in the same orientation as the target track Tko.

(2) A state in which only tracks of different orientations on the upstream side of the target track Tko are scanned.

(3) The state of partially scanning the upstream side of the target track Tko.

4) A state in which the entirety of the target track Tko is scanned without a tracking error.

5) Partially scanning the downstream side of the target track Tko.

(6) A state in which only tracks of different orientations on the downstream side of the target track Tko are scanned.

(7) The part which scans the downstream track Tkl of the same direction as the target track Tko partially.

The reproduction RF signal level at the magnetic heads 1 and 10 in each state of FIG. 3 changes as shown in FIG. 4 with the tracking error toward the upstream in the forward direction. Then, in the tracking control system based on the reproduction RF signal, the traveling speed V _t of the magnetic tape T is added or subtracted so that the reproduction RF signal level becomes ④. That is, in the case where tracking is deviated to the upstream side as in the state of (3), the traveling speed of the magnetic tape T is decelerated as shown by the arrow V _{t- in} FIG. That is, in the case where tracking is deviated to the downstream side as in the state of ⑤, the traveling speed V _t of the magnetic tape T is accelerated as shown by the arrow V _{t +} in the fourth way. V _h also represents the track scan speed of the magnetic heads 1 and 10.

The detection output EV of the envelope detector 12 is supplied to the CPU 21 of the digital servo control circuit (microcomputer) 20 via the A / D conversion circuit 22.

The timer 23 of the digital servo control circuit 20 is supplied with outputs of PG4 and FG5 attached to the rotating drum 2, and the output of the timer 23 is supplied to the CPU 21. From the CPU 21, the tracking control output CX is supplied to the driver amplifier 9 via the D / A conversion circuit 24.

The detection output EV supplied from the envelope detector 12 is compared with the reference power supply Vref by the comparator 13. For example, when the detection output EV is greater than the reference power supply Vref, the high level control signal Sc is supplied to the driver amplifier. When the detection output EV is smaller than the reference power supply Vref, the low level control signal is supplied. Sc is supplied to the driver amplifier 9. The gain of the driver amplifier 9 is controlled by the control signal Sc.

For example, the gain of the driver amplifier 9 is set to a low value when the reproduction RF signal level is in the range below the dashed line in FIG. 5, and the drive amplifier 9 in the range above the dashed line in the fifth state during the reproduction RF signal level. The gain of is set to a high value. As a result, the gain of the servo system is appropriately adjusted.

In this embodiment, the gain of the driver amplifier 9 is adjusted in two stages at a high and low reproduction RF signal level. However, the gain is not limited to this, but may be adjusted in multiple stages. Further, data for correcting the nonlinear characteristics of the reproduction RF signal level shown in the solid line in FIG. 5 as shown by the dashed-dotted line in FIG. 5 may be stored in the ROM, and the nonlinear characteristics may be continuously corrected based on this. .

The above-described tracking control output CX is amplified by the driver amplifier 9 to a predetermined gain and supplied to the motor 7.

The output of the FG8 on the capstan side is supplied to the digital servo control circuit 20 to perform normal capstan servo control, and the output of the digital servo control circuit 20 to the motor 3 is supplied to the normal drum servo. Control is performed.

Hereinafter, the circuit operation will be described with reference to FIG.

When the regeneration button 31 is operated and the VTR enters the regeneration mode, the CPU 21 determines whether or not the magnetic tape T is in an acceleration state based on the PG pulse from PG4, for example, once per field. The determination of whether or not the tracking control output CXn is positive or not is performed (step 111).

Then, whether or not the reproduction RF signal level of the current field has increased compared to the reproduction RF signal level of the preceding field, that is, the outputs EV _m and EV _{n-1 in} the current field and the preceding field of the envelope detector 12. ) Is compared (step 112 and 113).

According to the determination results of steps 111 to 113, the tracking states are classified into the following four types, and the tracking control output CX corresponding to each state is provided.

When the magnetic tape T is accelerating and the regenerative RF signal level is increasing, the magnetic heads 1 and 10 are in the same tracking state as ⑤ in FIG. The positive tracking control output CX _{n + 1} 0 for acceleration is obtained (step 114).

When the magnetic tape T is accelerating and the RF signal level is decreasing, the magnetic heads 1 and 10 are in the same tracking state as ③ in the third way and are controlled in the opposite direction to the stable direction. Negative tracking control output CX _{n + 1} 0 (step 115).

When the magnetic tape T is decelerating and the RF signal level is increasing, the magnetic heads 1 and 10 are in the same tracking state as ③ in FIG. 3 and are controlled in the stable direction. For the negative tracking control output CX _{n + 1} 0 (step 116).

When the magnetic tape T is decelerating and the RF signal level is decreasing, the magnetic heads 1 and 10 are controlled in the opposite direction to the stable direction when the magnetic heads 1 and 10 are in the same tracking state as ⑤ in the third way. This results in positive tracking control output CX _{n + 1} 0 for acceleration (step 117).

The error signal Ser is output in accordance with each of the tracking control outputs CX of steps 114 to 117 (step 118), and is supplied to the driver amplifier 9.

The above-described error signal Ser is amplified by the driver amplifier 9 with gain adjustment appropriately corresponding to the reproduction RF signal level, supplied to the motor 7, and the tracking error is corrected. In this way, the increase and decrease of the reproduction RF signal level in the acceleration and deceleration states of the magnetic tape T are respectively determined, and the traveling speed of the magnetic tape T is controlled based on the results of the two determinations. Tracking control can be performed.

In addition, the increase and decrease of the reproduction RF signal level is determined, the traveling speed of the magnetic tape T is controlled based on the determination result, the nonlinear characteristic of the change in the reproduction RF signal level is corrected, and the gain of the driver amplifier 9 is adjusted. Therefore, stable tracking control can be performed.

In this embodiment, only the polarity of the tracking control output CX has been described, but the present invention is not limited thereto. For example, the amplitude of the tracking control output CX may be determined based on the maximum value of the pre-stored reproduction RF signal level, and according to the difference between the reference and the reproduction RF signal level, or +0.1 V or -0.1 V. It is also possible to vary the polarity at a constant amplitude as shown.

This embodiment is similarly applied to a helical scanning digital audio tape recorder.

In this embodiment, a magnetic head Wh having a width equal to the track width Wtk is used. When a magnetic head wider than the track width Wtk is used, a known tracking control method (for example, Japanese Patent Laid-Open No. 62-A) is used. 222459) may be used together.

[Effects of the Invention]

According to the magnetic recording and reproducing apparatus according to the present invention, since the gain of the servo system is controlled according to the level change of the reproduction high frequency signal by correcting the nonlinearity of the level change of the reproduction high frequency signal outputted from the rotating magnetic head, stable tracking control can be performed. There is an effect that the tracking control can be performed with high accuracy with low cost and a simple configuration.

Claims (1)

A magnetic recording and reproducing apparatus in which a recording track inclined on a magnetic tape is inclined on a rotating magnetic head to obtain a reproduction signal, wherein the signal level discriminating means for determining the increase or decrease of the level of the reproduction high frequency signal output from the rotating magnetic head. And means for controlling the traveling speed of the magnetic tape based on the discrimination output of the signal level discriminating means, and gain correction means for correcting the nonlinearity of the level change of the reproduction high frequency signal with respect to the tracking error. Magnetic recording and reproducing apparatus, characterized in that.

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