JP2793739B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a magnetic tape, and more particularly to a structure for realizing stable running of a magnetic tape at a constant speed.

[0002]

2. Description of the Related Art In a conventional magnetic recording / reproducing apparatus using a magnetic tape, as a method of driving the magnetic tape at a constant speed, a pinch roller is pressed against a capstan shaft, and the capstan is held at a constant speed with a magnetic tape interposed therebetween. A method of realizing a constant speed running of the magnetic tape by rotating the magnetic tape is widely and generally used.

[0003]

However, a magnetic recording / reproducing apparatus which realizes a constant speed running of a magnetic tape by using a conventional capstan requires a mechanism for winding the magnetic tape on a tape winding reel. Also, since the diameter of the magnetic tape that can be wound on the tape take-up reel changes, a slip mechanism or the like is required in the power transmission section to the reel, which is extremely complicated in structure and cost. It was a problem.

Further, in a magnetic recording / reproducing apparatus which realizes a constant speed running of a magnetic tape by detecting the tape speed and directly controlling the rotation speed of a tape winding reel drive motor, the tape speed is detected and the tape winding is performed. Since the magnetic tape itself is included in the control system that controls the rotation speed of the reel drive motor, the control system changes due to a change in the state of the magnetic tape wound around the reel, such as a change in diameter or uneven winding.
This has adversely affected the realization of constant speed running of the magnetic tape.
In particular, in a control system that detects the tape speed and controls the number of revolutions of the tape take-up reel drive motor, it relates to the anti-resonance caused by the total equivalent moment of inertia of the magnetic tape and the tape supply reel, and to the magnetic tape and the tape take-up reel. There is a total equivalent moment of inertia and a resonance caused by the total equivalent moment of inertia of the tape supply reel, which detects the tape speed and limits the transmission characteristics of the control system that controls the rotation speed of the tape take-up reel drive motor. This caused the magnetic tape to degrade the constant speed running performance, that is, the wow and flutter.

The present invention has been made to solve the above-mentioned problems, and has a structure in which a tape speed is detected, a rotation speed of a tape take-up reel drive motor is directly controlled, and a magnetic tape runs at a constant speed. It is an object of the present invention to provide a magnetic recording / reproducing apparatus which achieves a significant cost reduction by simplification and realizes stable running of a magnetic tape at a constant speed.

[0006]

According to the present invention, there is provided a magnetic recording / reproducing apparatus for recording or reproducing information on a magnetic tape with a magnetic head. A magnetic tape speed detecting means, a tape driving reel reel driving means, and a control circuit for controlling a rotation speed of a reel driving motor of the tape winding reel based on speed information obtained by the tape speed detecting means; A magnetic recording / reproducing apparatus characterized by controlling the running speed of a magnetic tape by controlling the rotation speed of a reel drive motor of a tape take-up reel from speed information obtained by speed detecting means. Total equivalence for magnetic tape and tape take-up reels rather than the frequency of anti-resonance caused by the total equivalent moment of inertia for the tape supply reel The resonance frequency, which appears due to the inertia moment and the total equivalent moment of inertia of the tape supply reel, is set to be high during the recording and playback from the time when the magnetic tape starts to be wound around the tape take-up reel until the time when the winding ends. It is characterized by the following.

In the above magnetic recording / reproducing apparatus, in particular, a tape take-up reel drive motor, a speed reduction means driven by the tape take-up reel drive motor, a tape take-up reel base, a tape take-up reel, and a take-up reel. The equivalent moment of inertia of the magnetic tape roll about the rotation axis of the tape take-up reel is J _T , the radius of the magnetic tape wound on the tape take-up reel is R _T , and the contact between the magnetic head and the magnetic tape The spring constant in the longitudinal direction of the magnetic tape from the surface to the tape take-up reel is _KT , and the rotation axis of the tape supply reel of the tape supply reel base, the tape supply reel, and the magnetic tape roll wound by the tape supply reel. the equivalent inertia moment J _S around, or the contact surface of the winding diameter radius of the magnetic tape wound around the tape supply reel R _S, the magnetic head and the magnetic tape A longitudinal spring constant of the magnetic tape until the tape supply reel and K _S, during recording and playback, while the magnetic tape up to the point to be completely wound off from time to begin winding the tape take-up reel, K _S · R _S ² / J _S <K _S K _T / (K _S + K _T ) · (R _S ² / J _S + R _T ² /
J _T ).

[0008]

The present invention relates to a control system for detecting the speed of a magnetic tape, directly controlling the rotation speed of a tape winding reel drive motor, and realizing a constant speed running of the magnetic tape. The frequency of resonance caused by the total equivalent moment of inertia of the magnetic tape and the tape take-up reel and the frequency of resonance caused by the total equivalent moment of inertia of the tape supply reel is greater than the frequency of anti-resonance caused by the equivalent moment of inertia. By increasing the time between the start and end of winding on the take-up reel, the phase lag in the transfer characteristics of the control system is reduced, the servo band is improved, and the constant speed running performance of the magnetic tape is improved. Ie, an improvement in wow and flutter.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which a magnetic head is used as a means for detecting the speed of a magnetic tape, and a reel driving means uses a system in which a reel is directly driven by a motor. The magnetic tape 5 wound on the tape supply reel 3 is directly driven by rotating the tape winding reel drive motor 6 a to drive the tape winding reel drive motor 6 a, is transported, and is wound on the tape winding reel 2.
In this case, the reel drive motor 6b directly attached to the tape supply reel 3 is not controlled, and can be freely rotated. A tape speed detection signal of the magnetic tape 5 obtained from the magnetic head 1 is input to a tape speed calculation circuit 8, subjected to signal processing, and then input to a control circuit 9. The control circuit 9 compares the detected speed signal of the magnetic tape 5 with a preset traveling speed of the magnetic tape 5, that is, a target speed, and the obtained control signal is amplified by the amplifier circuit 10. The amplified control signal is input to the reel drive motor 6a after passing through the motor driver 11, and controls the rotation speed of the reel drive motor 6a. By switching the control signal output from the motor driver 11 to the reel drive motor 6a or 6b by switching the switch 12, bidirectional running of the magnetic tape 5 is realized. This is realized by rotating 6a or 6b at high speed.

Detecting the speed of the magnetic tape as shown in FIG.
In a magnetic recording / reproducing apparatus that realizes a constant speed running of a magnetic tape by directly controlling the rotation speed of a tape take-up reel drive motor, the anti-resonance caused by the total equivalent moment of inertia of the magnetic tape and the tape supply reel and the magnetic field There is a resonance due to the total equivalent moment of inertia for the tape and tape take-up reel and the total equivalent moment of inertia for the tape supply reel.

FIG. 2 is a transfer characteristic diagram of a control system of the magnetic recording / reproducing apparatus as shown in FIG. A in FIG. 2A is the resonance, and B in FIG. 2A is the anti-resonance. When the anti-resonance has a higher frequency than the resonance as shown in FIG. 2A, a sharp phase delay occurs near the resonance frequency as shown in C of FIG. 2B. This sudden phase delay limits the servo band in order to ensure the stability of the control system, and deteriorates the constant speed running performance of the magnetic tape, that is, the wow and flutter.

FIG. 3 is a transfer characteristic diagram in a case where the control system of the magnetic recording / reproducing apparatus as shown in FIG. 1 is configured so that the resonance has a higher frequency than the anti-resonance. FIG.
When the frequency of the resonance A is higher than that of the antiresonance B as shown in FIG. 3A, the phase advances near the antiresonance frequency as shown in FIG. The servo band is not restricted by the servo band, but the servo band can be improved.
That is, wow and flutter can be improved.

The resonance frequency and the anti-resonance frequency are as follows:
It is determined by the total equivalent moment of inertia of the reel, the radius of the magnetic tape wound on the reel, and the spring constant in the longitudinal direction of the magnetic tape. The anti-resonance frequency is the equivalent moment of inertia about the rotation axis of the tape supply reel of the rotating body that rotates while engaging with the magnetic tape and the tape supply reel from the contact surface of the magnetic head and the magnetic tape to the tape supply reel. The resonance frequency is a magnetic resonance between the magnetic tape and the magnetic tape between the contact surface of the magnetic head and the magnetic tape and the tape supply reel. Equivalent moment of inertia around the rotation axis of the tape take-up reel of the rotating body that rotates while engaging with the tape and the tape take-up reel, and around the rotation axis of the tape supply reel of the rotating body that engages with the tape supply reel and rotates This is the inherent resonance frequency with the equivalent moment of inertia.

In FIG. 1, the length of the magnetic tape 5 from the contact surface between the magnetic head 1 and the magnetic tape 5 to the tape supply reel 3 is L _S , the longitudinal elastic modulus is E _S , the width of the magnetic tape 5 is W, When the thickness is D, the spring constant K _S of the magnetic tape from the contact surface between the magnetic head 1 and the magnetic tape 5 to the tape supply reel _{3, K S = E S · W} · D / L S (gf / cm) Becomes Similarly, the length of the magnetic tape from the contact surface between the magnetic head 1 and the magnetic tape 5 to the tape winding reel 2 is L
_Assuming that _T and the longitudinal elastic modulus are E _T , the spring constant K _T of the magnetic tape from the contact surface between the magnetic head 1 and the magnetic tape 5 to the tape take-up reel 2 is: K _T = E _T · W · D / L _T (gf / cm). Here, the longitudinal elastic coefficients E _S and E _T of the magnetic tape 5
The difference is that the magnetic tape is a nonlinear elastic
The magnetic head 1 has a stress-strain relationship as shown in FIG.
The tape tension of the magnetic tape between the contact surface of the magnetic tape 5 and the tape take-up reel 2 and the tape tension of the magnetic tape between the contact surface of the magnetic head 1 and the magnetic tape 5 and the tape supply reel 3 are reduced. Because they are different.

The total moment of inertia of the tape supply reel 3 and the tape supply reel stand is J _RS , the moment of inertia of the roller of the tape supply reel drive motor 6b is J _MS , and the magnetic tape roll wound around the tape supply reel 3 is J _MS . When the moment of inertia and J _TS, total equivalent inertia moment J _S around the axis of rotation of the tape supply reel 3 becomes _{J S = J RS + J MS} + J TS (gf · cm · s 2). Similarly, the total moment of inertia of the tape take-up reel 2 and the tape take-up reel base is J _RS , the moment of inertia of the roller of the tape take-up reel drive motor 6a is J _MT , and the magnetic force wound around the tape take-up reel 2 is J _MT . When the moment of inertia of the tape roll and J _TT, the total equivalent inertia moment J _T about the rotational axis of the tape take-up reel 2 becomes _{J T = J RT + J MT} + J TT (gf · cm · s 2). However, when a speed reduction mechanism is used between the reel drive motor and the reel, the inertia moment of the roller of the motor must take into account the reduction ratio and the inertia moment of the speed reduction means driven by the motor.

Therefore, the anti-resonance frequency f _S is determined by setting the radius of the magnetic tape wound on the tape supply reel 3 to R _S.
Then, f _S = 1 / (2π) · (K _S · _RS ² / J _S ) ^1/2 (Hz), and the resonance frequency f _T is the magnetic tape wound on the tape take-up reel 2. Letting the radius of the winding diameter be R _T , f _T = 1 / (2π) · [K _S K _T / (K _S + K _T ) · (R _S ² / J _S + R _T ² / J _T )] ^{1 / 2} (Hz). Therefore, during recording and reproduction, in order to keep the resonance frequency higher than the anti-resonance frequency from the time when the magnetic tape is wound around the tape take-up reel to the time when the winding is finished, K _S · _RS ² / J _S <K _S K _T / (K _S + K _T ) · (R _S ² / J _S + R _T ² /
It can be seen that each element should be configured so that the relationship of J _T ) holds.

FIG. 5 is a transfer characteristic diagram when the resonance frequency is higher than the anti-resonance frequency and the difference between the frequencies is large. In the case of FIG. 5, since the gain is largely lost in the anti-resonance, it is difficult to greatly improve the constant speed running performance of the magnetic tape. Therefore, it is needless to say that the resonance frequency is higher than the anti-resonance frequency, and it is desirable to minimize the difference between the frequencies in order to greatly improve the constant speed running performance of the magnetic tape.

As described above, in the present embodiment, the total equivalent moment of inertia of the magnetic tape and the tape take-up reel and the tape supply reel are compared with the anti-resonance frequency that appears due to the total equivalent moment of inertia of the magnetic tape and the tape supply reel. By configuring the resonance frequency that appears due to the total equivalent moment of inertia to be high, the transmission characteristics of the control system prevent a sudden phase delay, secure the stability of the control system, and improve the servo band. The magnetic tape can be driven at a constant speed by the reel driving method.

[0020]

As described above, according to the present invention, the reel drive of the tape take-up reel is performed based on the speed information obtained by the speed detecting means of the running magnetic tape, the reel drive means of the magnetic tape take-up reel, and the tape speed detect means. By providing a control circuit that controls the number of rotations of the motor, it is possible to run a magnetic tape at a constant speed with a tape speed control system that does not use a capstan, a pinch roller, or a slip mechanism in the reel drive unit. It is excellent in realizing simplification, miniaturization, weight reduction and cost reduction of the device, and its practical effect is great.

Furthermore, due to the total equivalent moment of inertia for the magnetic tape and the tape take-up reel and the total equivalent moment of inertia for the tape supply reel, rather than the anti-resonance frequency that appears due to the total equivalent moment of inertia for the magnetic tape and the tape supply reel. The transmission characteristics of the tape speed control system can be improved by configuring the resonance frequency that appears as a higher frequency, and the constant speed running performance of the magnetic tape by the reel drive system, that is, the wow and flutter can be improved. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention.

FIG. 2 is a transfer characteristic diagram of a control system of the magnetic recording / reproducing apparatus of the present invention.

FIG. 3 is a transfer characteristic diagram of a control system of the magnetic recording / reproducing apparatus of the present invention.

FIG. 4 is a stress-strain diagram for a magnetic tape when the configuration of the present invention is used.

FIG. 5 is a transfer characteristic diagram of a control system of the magnetic recording / reproducing apparatus of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetic head 2 tape take-up reel 3 tape supply reel 4 cassette half 5 magnetic tape 6 reel drive motor 7 pad 8 tape speed calculation circuit 9 control circuit 10 amplifier circuit 11 motor driver 12 switch

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 15/46

Claims (2)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape with a magnetic head, comprising: a speed detecting means for a magnetic tape to be transferred; a reel driving means for a tape winding reel; and the tape speed detecting means. A control circuit for controlling the number of rotations of the reel drive motor of the tape take-up reel from the speed information obtained by the step (a), and the number of rotations of the reel drive motor of the tape take-up reel from the speed information obtained by the tape speed detection means. In the magnetic recording / reproducing apparatus, the running speed of the magnetic tape is controlled by controlling the magnetic tape and the frequency of the anti-resonance caused by the total equivalent moment of inertia of the magnetic tape and the tape supply reel. Moment of inertia for tape and tape take-up reels and total moment of inertia for tape supply reels A magnetic recording / reproducing apparatus characterized in that the frequency of the appearing resonance is increased during recording and reproduction from the time when the magnetic tape starts to be wound around the tape take-up reel to the time when the magnetic tape ends. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein a tape take-up reel drive motor, a speed reduction means driven by the tape take-up reel drive motor, a tape take-up reel base, a tape take-up reel, and a tape take-up reel. The equivalent moment of inertia of the magnetic tape roll wound around the take-up reel with respect to the rotation axis of the tape take-up reel is J _T , the winding radius of the magnetic tape wound around the tape take-up reel is R _T , The spring constant in the longitudinal direction of the magnetic tape from the contact surface with the magnetic tape to the tape take-up reel is K _T , the tape supply reel base, the tape supply reel, and the magnetic tape roll wound by the tape supply reel. The equivalent moment of inertia about the rotation axis of the supply reel is J _S , the radius of the magnetic tape wound on the tape supply reel is R _S , and the contact between the magnetic head and the magnetic tape is A longitudinal spring constant of the magnetic tape until the tape supply reel and K _S from Sawamen, during recording and playback, while the magnetic tape up to the point to be completely wound off from time to begin winding the tape take-up reel, K _S · R _S ² / J _S <K _S · K _T / (K _S + K _T ) · (R _S ² / J _S + _RT ² /
J _T ) is established.