JPH0512640A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] [Object] To obtain a magnetic recording / reproducing apparatus equipped with a magnetic head driving device capable of accurately tracing a magnetic recording trace on a magnetic tape. A magnetic head driving device provided with a subtractor 11b for feeding back an output of a magnetic velocity detector 33 to a magnetic recording / reproducing device, and an induced electromotive force element 33 by mutual induction.
An observer 11d that reproduces the same output as b and a subtractor 11e that subtracts the output of the observer 11d from the output of the magnetic velocity detector 33 are attached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a video tape recorder.
The present invention relates to a magnetic recording / reproducing apparatus having a rotary head assembly, such as a digital audio recorder, a digital audio pre-coder, and the like.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing a main part of a conventional magnetic recording / reproducing apparatus, and FIG. 6 is a VV arrow view of FIG. Figure 5,
In FIG. 6, 1 is a fixed drum, 2 is a bearing attached to the fixed drum, 3 is a rotating shaft supported by the bearing 2 and rotating, 4 is a pedestal fitted to one end of the rotating shaft 3, 5 Is a rotary drum mounted on the pedestal 4 with screws 6, 7 is a magnetic head driving device mounted on the rotary drum 5 with screws 8, and 9 is the fixed drum 1.
, A lower transformer 10 mounted on the pedestal 4, an upper transformer 11 mounted on the pedestal 4, a circuit board 11 mounted on the rotating drum 5, and a non-rotating contactor 12 for supplying a specified voltage to the magnetic head driving device 7. Is. Reference numeral 13 is a rotating electrode provided on a part of the pedestal 4 so as to be in contact with the contact 12, and 14 is a connection for electrically connecting from the electrode 13 to the magnetic head driving device 7 via the connecting portion 15 and the circuit board 11. Reference numeral 16 denotes a magnetic head attached to the magnetic head driving device 7, and is electrically connected to the upper transformer 10 via a connecting portion 17, a circuit board 11 and a connecting portion 15. Reference numeral 18 denotes a recess provided in a part of the rotary drum 5 for accommodating the magnetic head drive device 7, and is formed larger than the magnetic head drive device 7 so that the position of the magnetic head 16 can be adjusted. Reference numeral 19 is a position adjusting hole for adjusting the position of the magnetic head 16, and 20 is a magnetic tape fitted into the magnetic head 16.

FIG. 7, FIG. 8 and FIG. 9 show the magnetic head driving device 7 in more detail.
Is a first yoke made of a magnetic material, 22 is a column-shaped first permanent magnet fixed to the first yoke 21, and 23 has a convex portion 23b on a part of the inner circumference. A second yoke made of a magnetic material attached to the first yoke 21 and a third yoke 24 made of a magnetic material attached to the second yoke 23. Reference numeral 25 denotes a columnar second permanent magnet fixed to the third yoke 24 with the same magnetic pole as that of the first permanent magnet 22 facing each other, and 26 is provided between the second permanent magnet 25 and the first permanent magnet 22. And a pole piece made of a magnetic material fixed to either one of them. Reference numeral 27 denotes a leaf spring made of a thin non-magnetic material, which is sandwiched between the first yoke 21 and the second yoke 23, and the extending portion 27a thereof has the first yoke 21 and the second yoke 23. It projects outward through windows 21a and 23a provided in the yoke 23, and the magnetic head 16 is attached to the tip thereof. Reference numeral 28 denotes a leaf spring made of a thin non-magnetic material, which is the second yoke 23.
And is clamped by the third yoke 24. 29 is a leaf spring 2
The fixing members 30 and 30 respectively held by 7 and 28 are fixed to the fixing member 29 at a position where the inner circumference has a gap between the first permanent magnet 22, the second permanent magnet 25 and the outer circumference of the pole piece 26. A bobbin fixed with an adhesive 32, 31 is a coil made of an electric wire having a covering material wound around the bobbin 30, and 33 is an electric wire having a covering material wound around the bobbin 30 like the coil 31. In the magnetic velocity detector using the coil, the coil 31 and the magnetic velocity detector 33 have an annular gap between the convex portion 23b of the second yoke 23 and the entire circumference.

The operation of the above configuration will be described with reference to FIG. First, the first permanent magnet 22 generates a magnetic flux D by the closed magnetic circuit formed by the pole piece 26, the second yoke 23 and the first yoke 21. Similarly, the second permanent magnet 25
Generates a magnetic flux E in the opposite direction to the magnetic flux D due to the closed magnetic circuit formed by the pole piece 26, the second yoke 23 and the third yoke 24. The magnetic flux D and the magnetic flux E thus generated both traverse the annular gaps F and G in the same direction, and
The total magnetic flux of the first permanent magnet 22 and the second permanent magnet 25 crosses 1 and the magnetic velocity detector 33. In this state, when an electric current is applied to the coil 31 from the contact 12 through the electrode 13 and the connecting portions 15 and 14, the coil 31, the magnetic velocity detector 32, the bobbin 30 and the magnetic head 16 are integrated vertically in parallel. Make a linear motion. As a result, the magnetic head 16 is displaced in the width direction of the magnetic tape 20 and traces the magnetic recording trace with high accuracy.

Further, between both ends of the magnetic velocity detector 33,
Induced electromotive force proportional to the velocity of the magnetic velocity detector 33, which is generated by the magnetic velocity detector 33 performing a linear motion in a vertical direction across the total magnetic flux of the magnetic flux D and the magnetic flux E, and the coil 31 and the magnetic velocity. An induced electromotive force is generated by summing the induced electromotive force proportional to the value obtained by differentiating the current generated by the mutual induction between the detectors 33.

FIG. 10 shows a path for feeding back information from the magnetic velocity detector 33 to the magnetic head driving device 7, and 33a is a velocity detecting element for outputting an induced electromotive force proportional to the velocity of the magnetic velocity detector 33. , A is a speed detection element 33
a is an output, 33b is a mutual induction element that outputs an induced electromotive force proportional to a value obtained by differentiating a current generated by mutual induction between the coil 31 and the magnetic velocity detector 33, b is an output of the mutual induction element 33b, and c is The output of the magnetic velocity detector 33, which is the sum of the output a and the output b, 11a is an amplifier on the circuit board 11 for amplifying the output c and adjusting the feedback gain, 11b
Feeds the output of the amplifier 11a to the magnetic head driving device 7.
A subtracter on the circuit board 11 for driving back, 11c is a driver on the circuit board 11 for driving the magnetic head driving device 7 at a constant voltage, and v is a voltage input to the driver 11a.

FIG. 11 shows an equivalent circuit diagram of the magnetic head driving device 7 for output c, where L is the inductance component of the coil 31, R is the resistance component of the coil 31, and M is the coil 31.
2 shows the mutual inductance between the magnetic velocity detector 33 and the magnetic velocity detector 33. FIG. 12 shows frequency characteristics of sensitivity with respect to the voltages v of the outputs a, b and c, d of FIG. 13 shows frequency characteristics of driving current of the magnetic head 16 and sensitivity of displacement, and e shows constant voltage driving of the driver. As a result, the frequency characteristic of the sensitivity between the voltage v and the displacement of the magnetic head 16 is shown, and f shows the frequency characteristic of the sensitivity between the voltage v and the displacement of the magnetic head 16 with the feedback path.

In FIG. 13, the frequency characteristic d shows the characteristic of the second-order lag element because the magnetic head 16 is held by the leaf springs 27 and 28 and vibrates, and has a resonance peak.
As is clear from FIG. 11, the frequency characteristic e is that the driver 11a drives the inductance component L and the resistance component R of the coil 31 at a constant voltage, so that the cutoff frequency of the current input to the magnetic head drive device 7 is a primary of R / 2πL. The frequency characteristic e is a delay and a first-order delay is added to the frequency characteristic d. A time-differentiated version of this frequency characteristic e is the frequency characteristic of sensitivity to the voltage v of the output a in FIG. At this time, if the time differential is s and the sensitivity of the voltage to the speed determined by the geometrical conditions is K, the frequency characteristic of the sensitivity with the voltage v of the output a is represented by a / v = -Kse. Further, the frequency characteristic of sensitivity with respect to the voltage v of the output b is shown in FIG.
Since it is proportional to the mutual inductance M of B, it is represented by b / v = -Ms / (R + sL), and the gain shows M / L, and the cutoff frequency shows a high-pass filter characteristic of R / 2πL. From these, the sensitivity frequency characteristic with the voltage v of the output c is represented by c / v = -Kse-Ms / (R + sL).

As is apparent from FIG. 13, by feeding back the output c to the magnetic head driving device 7, the output a of the speed detecting element 33a of the magnetic speed detector 33 is fed back, and the magnetic The resonance peak in the frequency characteristic f between the drive current and the displacement of the head 16 is smaller than the resonance peak in the frequency characteristic e of the magnetic head 16, and the trace of the magnetic recording trace at the resonance frequency is stabilized.

[0010]

In the conventional resonance peak reduction method by the feedback path as described above, the output b by the mutual induction element 33b is also the magnetic head drive unit 7.
Since it is fed back, anti-resonance occurs in the output c of the magnetic velocity detector 33 at a frequency higher than the resonance frequency, and the output a of the velocity detecting element 33a is fed at that frequency.
Do not duck. Therefore, since the frequency characteristic f shows the sensitivity of the frequency characteristic e of the magnetic head 16 at the anti-resonance frequency, there is a problem that it becomes the resonance peak of the frequency characteristic f.

The present invention has been made to solve the above problems, and eliminates the resonance peak in the frequency characteristic of the sensitivity of the drive current and displacement of the magnetic head,
An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of improving the image quality by enabling an accurate trace of a magnetic recording trace.

[0012]

SUMMARY OF THE INVENTION A magnetic recording / reproducing apparatus according to the present invention is arranged at a position that moves parallel to the central axis of a rotating drum, like a magnetic head, and detects magnetic velocity of the magnetic head. And an observer for reproducing a state variable necessary for control by a detectable signal for driving a magnetic head driving device, speed information by the magnetic velocity detector and state variable information by the observer for the magnetic head. And means for feeding back to the drive device.

[0013]

According to the present invention, the output corresponding to the output of the mutual induction element reproduced by the observer is subtracted from the output of the magnetic velocity detector to erase the output of the mutual induction element, thereby driving the magnetic head. By feeding back only the output of the speed detecting element to the device, the resonance peak can be eliminated.

[0014]

【Example】

Embodiment 1 FIG. 1 shows a feedback path including an observer, showing an embodiment of the present invention.
b, 11c, 33, 33a and 33b are exactly the same as those of the conventional device. 11d is a mutual induction element 33b
Is an observer on the circuit board 11 which reproduces a signal corresponding to the output b of the above, and 11e is a subtracter on the circuit board 11 which subtracts the output of the observer 11d from the output c of the magnetic velocity detector 33.

The operation of the present invention will be described. In FIG. 1, the output c of the magnetic speed detector 33 is obtained by adding the output a of the speed detection element 33a and the output b of the mutual induction element 33b.
The frequency characteristic of sensitivity with respect to the voltage v of is expressed by c / v = -Kse-Ms / (R + sL). Further, the observer 11d outputs a signal having a frequency characteristic of -Ms / (R + sL) corresponding to the output b of the mutual induction element 33b. These outputs are the subtractor 1
The output b of the mutual induction element 33b is removed from the output of the subtracter 11e, and only the output a of the speed detection element 33a is output. The output of the subtracter 11e is amplified by the amplifier 11a, and the output of the amplifier 11a is subtracted by the subtracter 1a.
It is fed back to 1b.

FIG. 2 shows the observer 11d according to the present invention.
Shows a concrete circuit example of 34, an operational amplifier 34, a bias resistor 35, a bias power source 36, and C1, R1 and R2 external components of the operational amplifier 34 for determining the circuit gain and cutoff frequency. The frequency characteristic between the output of this circuit and the voltage v is represented by -sC1R2 / (1 + sC1R1), the gain is R2 / R1, the cutoff frequency is 1 / 2πC1R1, and C1, R1, and R2 are configured with appropriate values. Thus, the observer reproduces the output b of the mutual induction element 33b. Similar results are obtained in all circuits that can obtain the same frequency characteristics as this circuit.

In FIG. 3, g shows the frequency characteristic of the sensitivity of the drive current and displacement of the magnetic head 16 in the present invention. As is clear from FIG. 3, the magnetic velocity detector 33
By feeding back only the output "a" of the speed detecting element 33a in the output "c" to the magnetic head drive unit 7, the resonance peak in the frequency characteristic d of the sensitivity of the drive current and displacement of the magnetic head 16 can be eliminated.

Embodiment 2 FIG. 4 shows a feedback path in which an observer is added, showing another embodiment of the present invention, in which the driver 11c is driven by a constant current. At this time, since the first-order lag due to the inductance component L and the resistance component R of the coil 31 in FIG. 11 does not occur, the first-order lag element is provided in the preceding stage of the driver 11c, so that the observer 11d in FIG. The same structure as the bar 11d can be used.

[0019]

As described above, according to the present invention, the induced electromotive force due to mutual induction is erased from the information of the magnetic velocity detector, and only the induced electromotive force proportional to the velocity is fed to the magnetic head drive device. By performing the feedback, the resonance peak in the frequency characteristic of the sensitivity of the drive current and the displacement of the magnetic head can be eliminated, and therefore a stable trace of the magnetic recording trace with high accuracy can be obtained and the image quality is improved. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a feedback route including an observer according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a circuit example of an observer according to the first embodiment of the present invention.

FIG. 3 is a frequency characteristic diagram of the magnetic head according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a feedback route including an observer according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of a conventional magnetic recording / reproducing apparatus.

FIG. 6 is a view taken along the line VV of FIG.

FIG. 7 is an enlarged plan view of a main part of a conventional magnetic head driving device.

8 is a sectional view taken along the line VIII-VIII in FIG.

9 is a side view of FIG. 7. FIG.

FIG. 10 is a diagram illustrating a conventional feedback path.

FIG. 11 is a circuit equivalent diagram of a conventional magnetic head drive unit.

FIG. 12 is a frequency characteristic diagram of a conventional magnetic velocity detector.

FIG. 13 is a frequency characteristic diagram of a conventional magnetic head.

[Explanation of symbols]

 1 Fixed Drum 5 Rotating Drum 7 Magnetic Head Driving Device 11 Circuit Board 16 Magnetic Head 20 Magnetic Tape 33 Magnetic Velocity Detector

Claims (1)

Claim: What is claimed is: 1. A magnetic head movable parallel to a central axis of a rotary drum, a magnetic head driving device housed in the rotary drum, and the rotary drum rotatable via a bearing. In a magnetic recording / reproducing apparatus including a fixed drum that supports the magnetic head, a magnetic velocity detector that is arranged at a position that moves in parallel to the central axis of the rotating drum like the magnetic head and detects the velocity of the magnetic head, An observer for reproducing a state variable necessary for control by a detectable signal for driving the magnetic head driving device, speed information by the magnetic velocity detector, and state variable information by the observer to the magnetic head driving device. A magnetic recording / reproducing apparatus comprising means for feedback.