JPS6043216A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize recording and reproduction in various modes easly with extremely fast response by fixing magnetic heads at specific positions tightly through a position control servo-mechanism for a closed loop including a position measuring and controlling means for the magnetic heads, and transporting the heads to specific positions when the heads are not necessary. CONSTITUTION:A rotary head cylinder RHS is provided with magnetic heads Ha and Hb fitted to individual actuators ACTa and ACTb. Detection parts PDa and PDb vary in electrostatic capacity according to the displacement of movable arms 15a and 15b, and position signal generating means PSGa and PSGb output position signals corresponding to the displacement of the movable arms. The closed loop is formed in recording mode including the actuators ACT, PSG, subtracter 45, changeover switch 40, compensating circuit 47 for characteristics, changeover switch 39, and ACT, and the magnetic heads H are fixed at specific positions with a reference signal from a terminal 44. Further, the magnetic heads H are held at specific positions of the rotary head cylinder in reproducing operation to perform the reproduction.

Description

[Detailed description of the invention] (Industrial application field) The present invention provides magnetic i! 8. Recording/reproduction device' by Sugako.

(Prior art and problems) In order to realize high-density recording on magnetic tape, magnetic recording and reproducing devices have conventionally used a recording medium (1-rack r
Various methods have been attempted, such as narrowing the IJ) and applying tracking control to the magnetic head. There has also been provided a magnetic recording/reproducing device that performs tracking control by driving displacement.

By the way, when a bimorph plate of a piezoelectric element is used as an actuator for driving and displacing a magnetic head in the width direction of a recording trace for tracking control, the bimorph plate of a piezoelectric element has no flilJ movement. Because of this, it takes time to stabilize the position, and the bimorph plate of the piezoelectric element has basic mechanical resonance (primary vibration).
Since the secondary vibration has a frequency approximately twice as high as the frequency of the primary vibration described above, a servo loop that should be constructed using the bimorph plate of the piezoelectric element as an actuator must be constructed using a piezoelectric element. The piezoelectric bimorph plate used in the construction of the servo loop must be configured to operate in a frequency band below the frequency of the primary vibration of the bimorph plate (a). In the end, the amplitude becomes so small that it becomes difficult to use in practice.

Also, in the actuator of one example of a racking servo loop constructed using a bimorph plate of a piezoelectric element as an actuator, the frequency of its primary vibration is 400)1y.

A bimorph plate of a piezoelectric element of ~500Hy is used, and since the position of the magnetic head provided on this actuator is unstable, it cannot be used in recording mode. Separate from the attached magnetic head, a dedicated recording magnetic head is used that is fixed to the rotary head cylinder.

(Means for Solving the Problems) The present invention provides a rotary head cylinder having a magnetic head on its outer peripheral surface, an actuator for driving and displacing the magnetic head in 11 directions of recording traces on a magnetic tape, and the rotary head as described above. In a magnetic recording/reproducing device that includes a magnetic tape guide means for winding a magnetic tape around a predetermined portion of the outer peripheral surface of a cylinder and a magnetic tape transport means, a magnetic head whose drive is controlled by an actuator is used. A position signal generating means for generating a signal corresponding to the position of is provided in conjunction with the actuator, and
A magnetic recording/reproducing device comprising means for driving and controlling an actuator so that the signal generated by the position signal generating means is in a predetermined state, and a rotary head cylinder having a magnetic head on its outer peripheral surface. an actuator for driving and displacing a magnetic head in the width direction of a recording trace on the magnetic tape; a magnetic tape guide means for winding the magnetic tape around a predetermined portion on the outer peripheral surface of the rotary head cylinder; a tape transport means; a position signal generating means for generating a signal corresponding to the position of a magnetic head driven and controlled by an actuator; and a position signal generating means so that the signal generated by the position signal generating means is in a predetermined state. In a magnetic recording and reproducing apparatus equipped with means for driving and controlling an actuator, when reproducing an information signal recorded on a magnetic tape, a signal having a predetermined frequency and amplitude is applied to the actuator, and the above-mentioned position A magnetic recording/reproducing device is provided which is provided with means for driving and controlling the above-mentioned actuator based on a signal obtained by synchronously detecting a reproduced information signal using four signals generated by a signal generating means, thereby solving the problems of the prior art. It was designed to solve the problem.

(Example) Hereinafter, the specific contents of the magnetic φ]l' amphibian device of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the magnetic recording/reproducing device p1'' of the present invention, and FIG. 2 is an example of a head cylinder assembly consisting of a rotating head cylinder and a fixed cylinder. It is a vertical side view showing the configuration, and further includes:
FIG. 3 is an exploded perspective view of the rotary head cylinder and the actuator attached thereto.

In FIG. 1, magnetic l\rad a, Hb, actuators AC'J,' a are shown surrounded by a dashed-dotted line frame RH8.
, ACT b, and the position change detection units PDa and PDb in the position signal generating means.

This is a portion provided in the rotary head cylinder R1H8 in the head cylinder assembly shown in FIG. So, for the detailed configuration of the rotating head cylinder RH8 part, please refer to Figures 1 to 3 of the rotating head cylinder part 11jb in Figure 3. The general configuration of this will be explained.

In the head cylinder assembly shown in FIG.
IRH8 is a rotating head cylinder, SH8 is a fixed cylinder, and 1 is a rotating shaft. The rotating shaft 1 described above is supported by bearings 2 and 3 provided on the boss portion of the fixed cylinder SH3, and is driven and rotated at a predetermined rotation speed by a cylinder motor (not shown).

4 is a bushing fixed to the rotating shaft 1 described above, and this bushing 4 has a rotating head cylinder RH.
8 is fixed by screws 5, 5... and 1
One of the structural parts 6 (rotating side structural part) for relaying various signals between the rotating head cylinder side and the fixed cylinder side is attached.

7 cooperates with one of the components 6 for relaying various signals between the rotating head cylinder side and the fixed cylinder side, and transmits signals between the rotating head cylinder side and the fixed cylinder side. This is the other component (fixed side component) that relays various signals.

The above-mentioned two parts 6 and 7 are each provided with a No. 48 relay means using a rotary transformer, a signal relay means using a brush and a slip ring, etc., so that the above-mentioned surfaces can be met. Various signals can be relayed between the sections 6 and 7.

Reference numeral 8 denotes a tape guide provided on a part of the outer surface of the fixed cylinder SHS, and this tape guide 8 positions the edge of the magnetic tape T so that the magnetic tape is wound in a predetermined manner. Make sure it is wound diagonally around the cylinder.

The rotary head cylinder RH8 is provided with two sets of magnetic heads Ha and Hb attached to individual actuators ACTa and ACTb, respectively. In the illustrated example, the two sets of magnetic heads Ha and Hb are each shown as having two magnetic heads (two magnetic heads each are used as an erasing head and a recording/reproducing head, for example). irritating).

Next, referring to FIG. 3, the actuator ACTa rACT attached to the rotary head cylinder RH3 is
The configuration of b will be explained.

In FIG. 3, 9 is a hole into which the bushing 4 and rotating shaft 1 are fitted, and 10e and 10b are holes into which a part of the driving force generating portion of the actuators ACTa and ACTb is fitted. 12a is a cup-shaped magnetic path member that is fitted and fixed in the hole 10a, and 12b
1 is a cup-shaped magnetic path member that is fitted and fixed in the hole 10b, and the cup-shaped magnetic path members 12a and 1win are made of a magnetic material with high magnetic permeability.

Further, 13a and 13b are cylindrical permanent magnets, and one permanent magnet 13a is fixed to the center of the hole 10a, so that its outer peripheral surface and the cup-shaped magnetic path member 12a are connected to each other. A ring-shaped magnetic gap 1 between the inner peripheral surface
4a is formed. The other permanent magnet 13b is fixed to the center of the hole 10b, thereby forming a ring-shaped magnetic gap 14b between its outer peripheral surface and the inner peripheral surface of the cup-shaped magnetic path member 12b. let

16a and L6b are coils, one end of which is fixed to the movable arm 415a, and one coil i6a is positioned within the magnetic gap 14a without contacting the constituent members of the magnetic gap. Furthermore, the other coil 16b, one end of which is fixed to the movable arm 15b, is positioned within the magnetic gap 14b without contacting the constituent members of the magnetic gap. hand,
By supplying a current 1 to the coils 16a, ], 6b, the magnetic heads Ha, Hb attached to the movable arms 15a, 15b are driven and displaced in the width direction of the recording trace on the magnetic tape. ing. Permanent magnet 1
3a and 13b are magnetized in the direction of arrow M in the figure.

Both ends of the movable member 15a are provided with spring members 17al.
, 17a2, and fixed to the fixed portions 18al and 18a2. Further, both ends of the movable member 15b are connected to the fixed portion 18b via spring members 17bl and 17b2, respectively.
18b2.

The above-mentioned fixing parts 18al and 18a2 are connected to the spacer 19a.
to the rotating head cylinder RH8 through the screw 20a,
20b, and the aforementioned fixing portions], 8bl, and 18b2 are fixed to the rotary head cylinder RH8 via a spacer 19b with screws 27a and 27b.

That is, the screw 20a is screwed into the hole 21a of the fixing part 18a2, the hole 23a of the spacer 19a, and the threaded hole 24a of the rotating head cylinder RH8, and the screw 20b is screwed into the hole 24a of the fixing part 18a.
screwed into the hole 21b of b2, the hole 23b2 of the spacer 19a, and the screw hole 24h of the rotary head cylinder R'H8;
The screw 57a is connected to the hole 22a of the fixing part 18al and the spacer 19.
hole 25a of a, screw hole 26 of rotating head cylinder RH3
a, and the screw E7b is the fixing part 18b.
1, the hole 25b2 of the spacer 19b, and the threaded hole 26b of the rotary head cylinder RHS to form each actuator ACTa.

ACTb is fixed to the rotating head cylinder, cylinder RT-TS.

27a, 27b, 28a, and 28b are position change detection units PDa and PDb in the position signal generation means;
The electrodes 27a (27b) are provided on the movable arm]5a (], 5b) side, and
The electrode 283 (2813) is a permanent magnet 13a (], 3b)
is provided on the end face side.

The electrodes 27a and 28a are arranged to face each other, and when the movable arm 15a is driven and displaced, the electrodes 27a and 28a
In addition, the electrodes 27b and 28b are arranged to face each other, so that when the movable arm 5b is driven and displaced, the electrodes 27b and 28b rwI A change in the capacitance value is caused by the change in capacitance value.

FIG. 4 shows the position change detection section PDa described above.

FIG. 2 is a block circuit diagram of an example configuration of position ID generating means PSGa (PS(tb)) that generates a position signal based on a change in capacitance value that occurs in accordance with the amount of position change detected by Pdb. In FIG. 4, 29 is an oscillator, and this oscillator 29 generates an oscillation wave of frequency F9, which is transmitted to the coil 30 and the position change detection section ppa (Pnb
) is applied to the series resonant circuit formed by the capacitance value formed by the capacitance value. A coil 31 is electromagnetically coupled to the coil 30 described above.

The coil 30 described above and the position change detection section PDa (P D
5. When the movable arm 15a (15b) is at the center of displacement, the series resonant circuit constituted by the capacitance value formed between the two electrodes at F and F in FIG. It is designed to indicate a resonant frequency Fr expressed by r.

Then, the oscillation frequency F (I is) of the oscillator 29 described above.

A frequency value is selected such that when the series resonant circuit is resonating at the frequency Fr, the oscillation frequency Fq is located near the middle of the slope of the resonance curve of the series resonant circuit.

Therefore, the resonant frequency of the series resonant circuit is
, 15b, the frequency changes vertically around the frequency Fr as shown in FIG.

As a result, the impedance value of the series resonant circuit with respect to the oscillation wave of frequency Fq changes, so the current value of the oscillation wave of frequency Fq flowing through the coil 30 is
It changes according to the displacement of a and 15b.

2Δf in FIG. 5 indicates the change in the resonant frequency of the series resonant circuit that occurs according to the displacement of the iiJ a7-me, and 2Δi indicates the resonant frequency 2Δf of the series resonant circuit described above.
The current change occurring in the coil 30 in response to the change in is shown. Then, the frequency value flowing through the coil 30 is F q
A change in the current value of the oscillation wave ' causes a change in the output voltage of the coil 31 that is electromagnetically coupled to the coil 30.

Therefore, the position signal generating means P S G a (P
5Gb) output terminal 32 has a movable arm L5a,
A signal having a voltage value corresponding to the displacement of 15b, ie, a position signal, is output.

The second-order vibration type characteristic curve shown by the solid line in FIG. 6 shows the frequency versus amplitude characteristic of the mechanical system of the actuator configured as described above, and the resonant frequency fo is between the movable arm, the magnetic head, and the coil. The moment of inertia of the part such as
It is determined by the bending spring constant of the spring member.

In FIG. 1, the magnetic tape T is connected to the capstan motor 3.
The vehicle is driven at a predetermined traveling speed in the direction of the arrow X in the figure by a capstan 34 that is directly connected to and driven by the motor 3 and a pinch roller 35. (The magnetic tape T is wound in a predetermined winding manner around a head cylinder consisting of a rotating head cylinder RH8 and a stationary cylinder SH8 before traveling.

In FIG. 1, the state in which the magnetic tape T is wound around the head cylinder is not shown in order to simplify the illustration. ) As described above, one set of magnetic heads Ha and the other set of magnetic heads Hb are driven and displaced by individual actuators ACTa and ACTb, respectively.
The magnetic heads Ha and Hb of each set are provided in the rotary head cylinders R and H3, and each set of magnetic heads Ha and Hb is connected to each actuator AC.
For T a and ACT b, the control circuit CCa,
The actuators ACTa and ACTb are driven and displaced in the middle direction of the recording trace of the magnetic tape 1' by the drive displacement operation of the actuators ACTa and ACTb by the control drive signal supplied from CCb.
As described above, the actuator A CTa is provided with each set of magnetic heads Ha and Hb individually.

The control circuits CCa and CCb, which are provided to individually give control drive signals to the ACTb, are configured in the same purchasing form, so in the following description, the magnetic heads 11a and Hb , actuators ACTa, ACTb, control circuits CCa, CCb (
When a common explanation is given for each component (the same applies to each component), a common expression method is adopted in which the subscripts a and b are omitted to explain the common matters. It will be done.

In FIG. 1, FG is a frequency generator that detects the rotation angle of the rotating shaft of the capstan motor 34, and I)
C is a phase comparator, and this phase comparator pc compares the phase of the output signal of the frequency generator FG and the reference signal (for example, vertical synchronization signal) supplied to the terminal 36, and then The output signal is applied to the capstan motor 34 via the changeover switch 37, so that the running speed of the magnetic tape r in the recording mode is controlled.

38a, 38b, 39a, 39b, 40a, 40b, 4
1 and the like are changeover switches 38a, 38b, 39a, 39b, 40a, respectively.
, 40b and the changeover switch 37 described above, R is a fixed contact that is contacted by the movable contact in the recording mode, and P is a fixed contact that is contacted by the movable contact in the playback mode. In addition, the changeover switches 38a, 38b,
Even in the playback mode, the changeover switches 39a, 39b, etc. are set so that the movable contact is switched to the fixed contact R side while other sets of magnetic heads are playing back signals from the magnetic tape. Ru.

42a is an input terminal for the recording signal to be recorded on the magnetic tape T by the magnetic head Ha, and 42b is the magnetic head Hb.
43a is an output terminal for the reproduction signal reproduced from the magnetic tape T by the magnetic head Ha, and 43b is an output terminal for the reproduction signal reproduced from the magnetic tape T by the magnetic head Hb. Output terminals 44a and 44b are input terminals for reference signals to be applied to subtracters 45a and 45b for position fixing control of the magnetic head; 46a and 46b are narrowband bandpass filters; 47a and 4
7b, 48a, 48b, 53 are characteristic compensation circuits, 49
a and 49b are adders, 50a and 50b are envelope detectors, 51a and 51b are multipliers, and 52 is a signal generator (a wobbling signal generator).

The above-mentioned characteristic compensation circuits 47n, 47b, 48a, 48
In b, 53, the characteristic compensation circuit 53 is a characteristic compensation circuit for magnetic tape transfer control, and the characteristic compensation circuit 47
a.

47b is a characteristic compensation circuit for controlling the position fixing of the magnetic head during recording and a position fixing circuit for the magnetic head that is not in use during reproduction;
8a and 48b are characteristic compensation circuits for controlling the position of the magnetic head during reproduction.

Now, as described above, the actuator ACT to which the magnetic head H is attached has the open-loop characteristics of a secondary vibration system as shown by the solid line in FIG. , 47b, 48a, and 48b, the characteristics of the servo circuit including the actuator ACT are made as shown by the broken line in the figure, so that the loop gain becomes OdB at the frequency fc.

Since the movable arm 15 in the actuator ACT can be constructed so that its deflection resonance frequency is about 10 Kllz, it is possible to construct a servo circuit that can obtain a sufficient degree of improvement in a low frequency range of about 10 Hz.

First, when the magnetic recording/reproducing apparatus shown in FIG.
The movable contact 8a is switched to the fixed contact R side. In a state where the movable contact of the changeover switch 37 described above is switched to the fixed contact side 9, the capstan motor 33 → frequency power generation 4 & FG → phase comparator pc → changeover switch 37
→ A closed loop such as the capstan motor 33 is completed, and the capstan motor 33 rotates at the rotation speed determined by the reference signal supplied to the terminal 36, and the magnetic tape T
is transported at a predetermined constant speed.

In addition, by switching the respective movable contacts of the changeover switches 39 and 40 to the fixed contact R side, the actuator ACT→position signal detection means→subtractor 45
→ changeover switch 4o → characteristic compensation circuit 47 → changeover switch 39 → actuator 80T A closed loop such as The spatula H is placed in a fixed position at a predetermined position.

The resolution of position detection by detecting changes in capacitance has reached a sufficient level of 1 μm, and the degree of improvement of the servo loop is also sufficiently high. is reliably held with an error of 1 μm.

Therefore, in the magnetic recording/reproducing apparatus of the present invention.

As mentioned above, in the recording mode, the reference signal applied to the terminal 44 causes the magnetic head H to be securely and fixedly held at a specific position on the rotary head cylinder, that is, to maintain the state in which the magnetic head H is firmly held at a specific position on the rotary head cylinder. On the other hand, a recording operation can be performed in a state similar to that of a normal VTR having a structure in which a magnetic head is directly fixed. Also, during the reproduction operation, signals are reproduced from the magnetic tape while the magnetic head H is securely and fixedly held at a specific position on the rotary head cylinder in the same way as the operation in the recording mode described above. Of course, it is possible to do something.

Next, an explanation will be given of the operation in the case where the magnetic head attached to the actuator ACT performs a reproducing operation under tracking control.

In this playback mode, the changeover switch 37 has its movable contact switched to the fixed contact P side, and the two control circuits, the control circuit CCa and the control circuit ccb, are in contact with the magnetic tape T. magnetic tape T
The changeover switches 38, 39, 4 in the control circuit CC belonging to the magnetic head H which is reproducing signals from
0 is a changeover switch in the control circuit CC belonging to the magnetic head H which has its movable contacts switched to the fixed contact P side and is not reproducing signals from the magnetic tape T. 38, 39, and 40 have their movable contacts switched to the fixed contact R side, and the changeover switch 41 is a magnetic head whose movable contacts are reproducing signals from the magnetic tape T. The switch is switched to the fixed contact side connected to the fixed contact P of the changeover switch 40 in the control port/path CC belonging to H.

Each of the above-mentioned changeover switches 38 in the reproduction mode in which the magnetic head attached to the actuator ACT performs reproduction operation under tracking control.
Specific examples of the switching states of 41 to 41 are as follows.

That is, the two magnetic heads (magnetic head) ta and magnetic head Hb
If the magnetic head of the set of magnetic heads that is currently reproducing signals from the magnetic tape T is the magnetic head Ha as shown in the first diagram, then in this case, the magnetic head belonging to the magnetic head Ha is Changeover switch 3 in the control circuit CCa of
8a, 39R, and 40a have their movable contacts switched to the fixed contact P side, and
The movable contacts of the changeover switches 38b, 39b, and 40b in the control circuit CGb belonging to the magnetic head Hb are switched to the fixed contact R side, and the movable contact of the changeover switch 41 is switched to the fixed contact R side. This results in a state in which the fixed contact is switched to the a side.

Contrary to the above, if the magnetic head reproducing signals from the magnetic tape T is the magnetic head Hb, in this case, the changeover switches 38b, 39b, 40b in the control port mccb belonging to the magnetic head Hb The movable contacts of these are switched to the fixed contact P side, and the changeover switches 30a, 39a, 40a in the control circuit CCa belonging to the magnetic head Ha are switched to the movable contacts of these. is switched to the fixed contact R side, and furthermore, the movable contact of the changeover switch 41 is switched to the fixed contact R side.

Now, the reproducing operation when the magnetic head reproducing signals from the magnetic tape 1' is the magnetic head Ha will be explained as follows.

That is, in this case, the changeover switches 38a, 39a, in the control circuit CCa belonging to the magnetic head Ha
40a, as described above, those movable contacts are fixed contacts P.
Since the signal reproduced from the magnetic head Ha is switched to the movable contact of the changeover switch 38a and the fixed contact P.
It is applied to the output terminal 43a and the envelope detector 50a via the magnetic head Ha → the movable contact of the changeover switch 38a → the constant contact P → the envelope detector 50a → the multiplier 51a → the adder 49a. → Characteristic compensation circuit 48a → Fixed contact P of changeover switch 39a → Movable contact → Actuator A CTa → A closed loop of magnetic head Ha is formed, and a tracking control operation for the magnetic head J*a is performed.

Now, the multiplier 51a described above has a position signal generating means PS.
Since the signal component of a specific frequency Fa extracted by the narrowband bandpass filter 46a from the output signal of Ga (the signal component of the frequency Fa generated by the signal generator 52) is also supplied, in the multiplication 1151a, The output signal of the envelope detector 50a is multiplied by the above-described signal component of the specific frequency in the output signal of the position signal generating means PSGa, and the resulting output signal is applied to the adder 49a.

The adder 49a adds the output signal of the multiplier 51a and the signal of frequency Fa generated by the signal generator 52, and provides the output signal to the characteristic compensation circuit 48a,
The output signal from the compensation circuit 48a having the characteristics described above is supplied to the actuator ACTa via the changeover switch 39a, whereby the actuator 80Ta drives and displaces the magnetic head Ha in the direction of the recording trace on the magnetic tape. .

Since the actuator A CT a is given a signal with a frequency value Fa generated by the signal generator 52 described above, the magnetic head Ha wobbles the recording trace on the magnetic tape T at the frequency Fa. Become.

FIG. 7(a) shows the relationship between the amount of displacement (horizontal axis) and the reproduction output (vertical axis) when the magnetic head Ha is displaced from the center position of the recording trace. 7(b) shows the position signal generated by the position signal generating means in a state where the magnetic head Ha is still displaced as described above, and FIG. The actuator ACT is given a signal whose frequency value is Fa.
A indicates a state in which the magnetic head Ha is wobbling the recording trace on the magnetic tape T at a frequency Fa.

When the magnetic head Ha wobbles at a frequency F''a, the reproduction output of the magnetic head becomes 1 as shown in FIG. 7(d).
It is modulated at a frequency of 2Fa.

On the other hand, the output No. 43 of the position signal generating means PSGa is proportional to the displacement of the magnetic head +4a, as shown in FIG. 7(e).

The multiplier 51a described above outputs an output signal that is the product of the signal shown in FIG. 7(d) and the signal shown in FIG. 7(e). , resulting in a signal as shown in FIG. 7(f).

When the magnetic head Ha is at the center of the recording trace, the frequency F a
When the output signal from the multiplier 51a is driven by the magnetic head Ha, the output signal from the multiplier 51a becomes a signal with a symmetrical positive and negative waveform as shown in FIG. never changes.

However, if the magnetic head Ha is shifted, for example, to the right in Figure 7, the reproduction output of the magnetic head will be the minimum at the maximum value of the 1-position signal, and the signal waveform of the reproduction output will be as shown in (g) in Figure 7. , and the multiplier 51. The output signal from a has a waveform whose positive and negative sides are asymmetric, as shown in FIG. 7(h). This signal indicates the amount and direction of deviation of the magnetic head Ha. 6 Even if the magnetic head deviates in the opposite direction to the above, the output signal from the multiplier 51a Needless to say, it indicates the amount and direction of deviation of Ha.

As described above, since the output signal of the multiplier 51a is fed back to the actuator ΔCTa, tracking control is performed so that the magnetic head Ha always matches the recording trace.

Assuming that the vibration of actuator ACT is XI(s)=a cos 2 x Fat, the transmission function is as follows.

However, Y (s) is the movement wind of the magnetic head, and X (s) is the amount of positional deviation in which the position of the magnetic head deviates from the center of the recording trace when the servo loop is off. G (s) is the circular transmission of the tracking loop. Function (6th
(Open-loop characteristics shown in the figure) Therefore, the tracking error is E(s) = X(s) - Y(s) = (X(s) -
I(s))1+G(s).

Then, the frequency F is near the gain crossover frequency fc in FIG.
a, and that X (s) is considerably lower than the gain crossover frequency fc, and that G (s
) is approximately equal to 1, so the tracking error E (s) is finally: This result shows that wobbling vibration always remains as a trunk ranking error. In other words, wobbling servo is established.

The magnetic head Ha moves due to the tracking characteristic of the magnetic head to the recording trace during reproduction. If the magnetic onion tape T is not transferred correctly by the capstan 34, a direct current even-odd condition occurs in the output signal of the position signal generating means PSGa, and as a result, a direct current voltage is output from the subtractor 45a. This is the movable contact of the changeover switch 40a → the fixed contact P → the fixed contact a of the changeover switch 4J
→The same moving contact is supplied to the auxiliary M circuit 53 with temperature characteristics.

The DC output from the compensation circuit 53 having the above-mentioned characteristics is applied to the capstan motor 33 via the fixed contact P of the changeover switch 37 → the co-moving contact, and is thereby applied to the magnetic tape T.
The running speed of the position ID number generating means PSGa is changed, but this control operation brings the magnetic head Ha into a state where it correctly follows the recording trace of the magnetic tape T, and the output of the position ID number generating means PSGa reaches the terminal 44a.
This continues until the reference signal N (supplied to A) becomes equal to the reference signal A, and therefore the transport speed of the magnetic tape T is limited to the above.

Precisely maintained by movement.

Due to the above-mentioned reproduction state, that is, the state in which the magnetic head Ha is reproducing signals, the magnetic head Hb becomes cloudy.
The changeover switch 38b in the control circuit ccb belonging to
39b, 40b, etc., have the movable contacts on the side A switched to the fixed contact R side as described above. A closed loop is formed as follows: subtracter 45b → selector switch 40b → characteristic compensation circuit 47b → selector switch 39b → actuator ACTb, and this closed loop is connected to actuator A O by the base f1 signal supplied to terminal 44b. 'I' b causes the magnetic head Hb to be fixedly positioned at a predetermined position and placed in a rubbing state.Therefore, in the magnetic recording/reproducing apparatus of the present invention, the magnetic head Hb that is at rest is placed at a predetermined position when it enters a reproducing operation. The introduction operation into the record can be performed accurately.

The stiffness of the fixed position control system b), which is configured to include the position signal generating means PSG, is determined, for example, as follows.

That is, now, the resolution Δ of the servo is 1 μm, the frictional force F between the magnetic tape and the magnetic head is 0.3 gr, and the spring constant K of the actuator is K=F/Δ=300 gr/mm. The oven loop gain shown in 9 is 60 for the DC component.
In dB, stiffness G-K = 300 K gr/m
The magnetic head can be fixed in place reliably due to the high stiffness described above. Theoretically, the positional error of the magnetic head is Δ.

The applicant company has proposed that variable speed playback, special recording and playback, etc., be performed by a magnetic recording and reproducing device configured such that two sets of magnetic heads are driven and controlled by individual actuators. ing(
It is clear that the magnetic recording/reproducing apparatus of the present invention can perform the variable speed reproduction, special recording/reproducing, etc. performed in the previously proposed magnetic recording/reproducing apparatus. be.

Furthermore, since the magnetic recording and reproducing apparatus of the present invention can perform recording and reproducing operations with the magnetic head fixed at a specific position, it is also possible to perform operations in the following special recording and reproducing modes. can.

First, during recording, the magnetic tape T is run as usual, and a constant reference signal (reference voltage) as shown in FIG. 8(a) is applied to the terminal 44 for recording. During playback, With the capstan motor stopped, the movable contacts of the changeover switches 39 and 40 are switched to the fixed contact R side, and the reference signal supplied to the terminal 44 is set as shown in FIG. 8(b).
A sawtooth wave is created as shown by the broken line and solid line to cause the magnetic head to respond as shown by line A, and the solid line section A't'' causes the magnetic head to correctly follow the recording trace on the magnetic tape by controlling the oven loop. In this case, the sawtooth wave shown by the broken line and the solid line on the 8th day (b,) allows the magnetic head to correctly follow the recording trace on the magnetic tape to the solid line section. If this is done properly, open-loop control can provide good still playback.

Then, during reproduction in the above-mentioned reproduction mode, one magnetic head receives the reference signal (
Since the required displacement operation can be performed with sufficient time margin (for example, the time constant of the servo system is 1 ms, 7 sections Δ, B
(The time length of section 1vIA is 16 m5.) When performing playback in this playback mode, switch the movable contacts of changeover switches 39 and 40 to the fixed contact P side at the start of section A, and change the solid line section of section 1vIA. Instead of the open-loop control described above, the magnetic head may follow the recording trace as the reproduction wobbling control described above.

Next, a recording trace is formed on the magnetic tape T, which is running normally, with a recording trace in the same state as the recording trace drawn on the magnetic tape when the magnetic tape is stopped. Next, an embodiment of recording/reproducing in another special form in which recording/reproducing is performed will be described.

In this embodiment of recording and reproduction, the magnetic head records and forms a recording trace having an inclination angle (stop angle) equal to the stop angle of the tape on the magnetic tape running at a standard running speed during recording. A sawtooth wave voltage as shown in (a) of the figure is supplied to the terminal 44 to form successive recording marks on the magnetic tape.

Therefore, recording traces similar to the recording traces formed when the magnetic tape is stopped are formed one after another on the magnetic tape.

When reproducing a recorded magnetic tape on which recording traces have been formed as described above, a constant reference signal (reference voltage) is applied to the terminal 44 as shown in FIG. If a magnetic head is used to reproduce signals from a stopped magnetic tape, good still reproduction can be achieved. The most important feature of this recording/playback method is that since recording traces are formed on the magnetic tape at stop angles, editing such as mixed recording of still images and videos, and updating of records for each recording trace is possible. This is something that can be done freely.

In addition, in order to control frame-by-frame shooting or single-frame playback of still images, it is necessary to perform pulse numerical control on the capstan motor to intermittently transport the magnetic tape.
Such a thing can be done easily.

The recorded magnetic tape, on which recording traces are recorded and formed at the stop angle as described above, is then played back and forth in forward and reverse playback directions and playback speeds, centering on the still playback mode, with the reference signal (
The reference voltage) and the voltage supplied to the capstan motor are determined symmetrically.

Next, in the magnetic recording/reproducing apparatus of the present invention, the height of each magnetic head can be determined independently.

For example, if the height of each magnetic head is the same and each magnetic head follows the same trajectory, the signal recorded by one magnetic head can be immediately reproduced by the other magnetic head, and the recorded content can be reproduced. It is easy to monitor,
Important functions can be added to information equipment.

In addition, in carrying out the present invention, one
The magnetic recording/reproducing apparatus of the present invention may be configured to include only one set of magnetic heads. If only one set of magnetic heads were used, rapid transfer of the magnetic head between tracks during special playback would be required, but the closed-loop position control servo device of the present invention is extremely effective. Can effectively adapt to the demands. That is, in the control system described above, its time constant is determined by the gain intersection frequency fc in FIG. 6, and exhibits an extremely high response. For example, if the gain father point frequency fc is I
At KHz, the time constant is approximately Ims, and the non-operating time of the magnetic head can be made extremely small. Furthermore, as mentioned above, because the error of the position control mechanism of the present invention is small, special reproduction can be performed satisfactorily even if only one set of magnetic spatulas is provided on the rotating head cylinder. be.

(Effects) As is clear from the above detailed explanation, the present invention includes a rotary head cylinder equipped with a magnetic head on the outer peripheral surface, and an actuator that drives and displaces the magnetic head in the rlJ direction of the recording trace on the magnetic tape. , the above rotation
In a magnetic recording and reproducing apparatus that includes a magnetic tape guide means for winding a magnetic tape around a predetermined portion of the outer peripheral surface of a head cylinder and a magnetic tape transport means, a magnetic tape whose drive is controlled by an actuator is used. A magnetic device comprising a position signal generating means for generating a signal corresponding to the position of the head, and a means for driving and controlling an actuator so that the signal generated by the position signal generating means is in a predetermined state. A recording/reproducing device that uses a closed-loop position control servo mechanism that includes magnetic head position measurement and control means to firmly fix the magnetic head position at a predetermined position when necessary, and Therefore, in the magnetic recording/reproducing apparatus of the present invention, recording/reproducing in various modes, special recording/reproducing, etc. can be easily realized with small errors and extremely fast response.

Furthermore, in the magnetic recording/reproducing apparatus of the present invention, since the absolute position of the magnetic head can be accurately determined from the measurement results, the tracking servo operation of the recording trace can also be performed accurately using the same M detection method based on the reproduction output of the magnetic head. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the magnetic recording/reproducing apparatus of the present invention, and FIG. 2 is a longitudinal cross-sectional side view of a /\rad cylinder.
Fig. 3 is an exploded perspective view of the rotary head cylinder and actuator, Fig. 4 is a block circuit diagram of an example of the configuration of the signal generating means, Figs. 5 to 7 are characteristic curve examples, and Fig. 8 The figure and the 9th part do not show the change mode of the base voltage (I = multiplied signal reference voltage) on the time axis. T... Magnetic tape, ACTa, ΔOT)
Actuator, P S G a + T) S (, +
b...Position signal generating means, PDa, PDb...Position change detection unit, IX1°Hb...Magnetic head, R
) (S... Rotating head cylinder, S HS... Fixed cylinder, PC... Phase comparator circuit, FG... Frequency generator, CCa, CCb... Control circuit, 15 a, 15
b"・Movable arm, 37.38 a~40 a, 3
8 b-40b, 41... changeover switch, 44a,
44b... Reference signal input terminal, 45a. 45 b...Subtractor, 47 a g 47 b g
48 a t48b, 53-characteristic compensation circuit, 50a
, 50b...envelope detector, 51a, 51b...multiplier, 52...-signal generator,

Claims (1)

[Scope of Claims] 1. A rotating head cylinder having a magnetic head on its outer circumferential surface, an actuator for driving and displacing the magnetic head in the width direction of a recording trace on a magnetic tape, and a predetermined position on the outer circumferential surface of the rotating head cylinder. In a magnetic recording/reproducing apparatus comprising a magnetic tape guide means for winding a magnetic tape around a portion of the magnetic tape and a magnetic tape transport means, a signal corresponding to the position of a magnetic head driven and controlled by an actuator is provided. A magnetic device comprising a position signal generating means for generating a position signal, which is associated with the actuator, and a means for driving and controlling the actuator so that the signal generated by the position signal generating means is in a predetermined state. A recording/reproducing device 2, a rotary head cylinder having a magnetic head on its outer circumferential surface, an actuator for driving and displacing the magnetic head in the width and direction of a recording trace on a magnetic tape, and a predetermined portion on the outer circumferential surface of the rotary head cylinder. a magnetic tape guide means for winding a magnetic tape around a magnetic tape; a magnetic tape transport means; a position signal generating means for generating a signal corresponding to the position of a magnetic head driven and controlled by an actuator; In a magnetic recording and reproducing apparatus, which is equipped with a means for driving and controlling an actuator so that the signal generated by the position signal generating means is in a predetermined state, when reproducing an information signal recorded on a magnetic tape, the actuator A signal having a predetermined frequency and amplitude is applied to the position signal generator, and the drive control of the actuator is performed based on a signal obtained by synchronously detecting the reproduced information signal using the signal generated by the position signal generating means. A magnetic recording/reproducing device comprising a means for