JPH052727A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a device whose constitution is simple, and which can be easily assembled by displacing a magnetic head upward and downward through a plate spring interposed between an upper yoke and a lower yoke. CONSTITUTION:As for a magnetic head driving part 40, a plate spring 43 is interposed between an upper yoke 41 and a lower yoke 42, a magnetic head 12 is attached to the top end of an extended part 43a of the plate spring 43, and a coil 46 or permanent magnets 44 and 45 are fixed to the plate spring 43. Then, the permanent magnetic stones 44 and 45 opposed to each other to an axial direction through a gap, or the coil 46 is fixed to at least either the upper yoke 41 or the lower yoke 42. The magnetic head 12 is driven and displaced upward and downward through the plate spring 43 by allowing driving currents to flow to the coil 46, so that the number of parts of the driving part can be reduced, and the device whose constitution is simple, and which can be easily assembled, can be obtained.

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 provided with a rotary head assembly such as a video tape recorder and a digital video tape recorder, and more particularly to improvement of a magnetic head driving section.

[0002]

2. Description of the Related Art FIG. 9A is a longitudinal sectional view of a rotary head assembly of a conventional magnetic recording / reproducing apparatus disclosed in Japanese Patent Laid-Open No. 64-53320, and FIG. 9B is FIG. 9A. Is a cross section taken along line B ₉ -B ₉ of FIG. In FIG. 9, 1 is a magnetic tape, 2
Is a fixed cylinder provided with a lead groove 2a for guiding the magnetic tape 1 on its outer peripheral surface, and 3 is a rotary shaft rotated by a drive motor (not shown), which is supported by the fixed cylinder 2 via a bearing 4. 5 is a pedestal fixed to the rotating shaft 3, 6 is a rotary cylinder fixed to the pedestal 5, 7 is a rotary transformer, and a fixed side transformer 8 is attached to the fixed cylinder 2.
And a rotation side transformer 9 attached to the pedestal 5 and corresponding to the transformer 8 via an air gap. Reference numeral 10 denotes a magnetic head drive unit mounted by a mounting screw 11 in the recess 6a of the rotary cylinder 6, which supports the magnetic head 12 and moves it vertically. Reference numeral 13 is a relay wiring board attached to the rotary cylinder 6, and 14 is a fixed-side contactor for supplying a control current to the rotary head assembly of the magnetic recording / reproducing apparatus from outside, to the magnetic head drive unit 10, such as a brush. Become. Reference numeral 15 is an electrode that is attached to the upper part of the pedestal 5 and rotates integrally.
Being touched by 14. The magnetic head 12 is electrically connected to the rotating-side transformer 9 via the connecting portion 17, the wiring board 13, and the connecting portion 16. The arrow T indicates the running direction of the magnetic tape 1, and the arrow S indicates the rotating direction of the rotary shaft 3 and the rotary cylinder 6.

Next, the magnetic head drive unit 10 is shown in FIGS. 10 (A) and 10 (B).
And (C) are a plan view, a vertical sectional view and a side view. In FIG. 10, reference numerals 21, 22 and 23 denote a first yoke, a second yoke and a third yoke which are made of a magnetic material and are coupled to each other. An annular magnetic pole portion 22b is formed on the inner circumference of the second yoke 22. Reference numerals 21a and 22a are window holes provided in the yokes 21 and 22 to project the magnetic head 12. Mounting holes for yoke 23a 23a
Is provided. Reference numeral 24 is a cylindrical first permanent magnet fixed to the yoke 21, and 25 is a first permanent magnet fixed to the yoke 23.
A cylindrical second permanent magnet having the same polarity as that of 24 and facing in the axial direction,
Reference numeral 26 is an iron core arranged between the permanent magnets 24 and 25 and fixed to one of the permanent magnets. 27 is a first leaf spring made of a thin plate of a non-magnetic metal material, which is provided with a plurality of circumferential slits from the outer circumference side to the inner circumference side, and is provided with springiness, and the inner circumference side is provided. From the window holes 21a and 22a, and the magnetic head 12 is attached to the tip. The leaf spring 27 is sandwiched between the yokes 21 and 22 on the outer circumferential side. Reference numeral 28 denotes a second leaf spring made of a thin plate of a non-magnetic metal material, which is provided with a plurality of circumferential slits from the outer circumferential side to the inner circumferential side so as to have springiness, and the outer circumferential side has a yoke. It is sandwiched between 22 and 23. Reference numeral 30 denotes a cylindrical bobbin, the inner circumference of which is provided with a gap in the outer circumferences of the permanent magnets 24 and 25 and the iron core 26, and the fixing members 29 which are held on the inner circumferences of the leaf springs 27 and 28, respectively, by an adhesive. It is fixed. Reference numeral 31 denotes a coil in which an insulated conductor is wound around the bobbin 30, and a gap is provided over the entire circumference between the bobbin 30 and the inner circumference of the annular magnetic pole portion 22b of the yoke 22. G is a radial air gap between the iron core 26 and the annular magnetic pole portion 22b.

The operation of the rotary head assembly of the conventional magnetic recording / reproducing apparatus will be described with reference to FIG. First, when the rotary cylinder 6 is rotated by driving the rotary shaft 3, the magnetic head 12 is also rotated around the rotary shaft 3, and the lead groove 2a
Information is recorded on or reproduced from the magnetic tape 1 which is guided along and runs along the outer circumferential surfaces of the fixed cylinder 2 and the rotary cylinder 6. At this time, the recorded or reproduced information is transmitted from the magnetic head 7 to the rotating-side transformer 9 and is transferred via the fixed-side transformer 8 to the fixed-side signal processing circuit in a non-contact manner.

Next, the operation of the magnetic head drive section 10 will be described with reference to FIG. The permanent magnet 24 generates a magnetic flux D in the closed magnetic circuit formed by the iron core 26, the annular magnetic pole portion 22b, and the yokes 22 and 21. Further, the permanent magnet 25 generates E in the closed magnetic circuit formed by the iron core 26, the annular magnetic pole portion 22b, and the yokes 22 and 23 in the direction opposite to the magnetic flux D. The magnetic fluxes D and E pass through the annular air gap G in the same direction and cross the coil 31. In this state, when a drive current is applied to the coil 31 via the contactor 14 and the electrode 15, the coil 31
Moves reciprocally in the vertical direction (direction parallel to the rotating shaft 3) integrally with the bobbin 30, the extending portion 27a and the magnetic head 12. At this time, the magnetic head 12 moves to the magnetic tape 1 as shown in FIG.
On the other hand, by reciprocating in the direction orthogonal to the magnetic recording trace 34, the magnetic recording trace 34 can be traced accurately and a good reproduction signal can be obtained. The arrow T indicates the running direction of the magnetic tape 1, and the arrows S and W indicate the rotating direction and reciprocating direction of the magnetic head 12. Reference numeral 35 is a magnetic recording trace that deviates from the predetermined standard. To record a signal, a constant drive current is passed through the coil 31 and the magnetic head 7 is fixed at a predetermined height, so that a predetermined magnetic recording mark 34 is formed on the magnetic tape 1.

FIG. 12 is a vertical sectional view showing another example of a conventional magnetic head drive section. The magnetic head drive unit 10 includes a second yoke made of a magnetic material between a first yoke 21 and a third yoke 23.
36 is fixed, and a cylindrical permanent magnet is provided inside the second yoke 36.
37 is stuck. The permanent magnet 37 is magnetized with different polarities on the inner peripheral side and the outer peripheral side. The yoke 36 is provided with a window hole 36a through which the extending portion 27a of the leaf spring 27 is exposed. 38 is the yoke 21
It is an iron core made of a magnetic material, which is arranged between the two yokes and is fixed to one of the yokes. An air gap G is formed between the inner circumference of the permanent magnet 37 and the outer circumference of the iron core 38. Note that 12, 27, 27a, and 28 to 31 are the same as in FIG. 11 (B) above.

In the magnetic head drive unit 10 of FIG. 12, by energizing the coil 31, the magnetic head 12 is reciprocated in the vertical direction or maintained at a predetermined height position as in the case of FIG. 11B. be able to.

[0008]

In the conventional magnetic recording / reproducing apparatus as described above, the number of parts of the magnetic head drive section 10 is large, the assembly is troublesome, time-consuming and expensive, and further, the size and weight are reduced. There was a problem that it hindered.

Further, it is desirable that the air gap G has the same size in the radial direction, and the positions of the bobbin 30 and the coil 31 in the air gap G in the radial direction are even. The main components that determine the dimensions of the air gap G and the positions of the bobbin 30 and the coil 31 in the radial direction include the second yokes 22 and 36, the annular magnetic pole portion 22b,
Although there are the permanent magnets 37, the leaf springs 27 and 28, the fixing member 29, and the bobbin 30, the accumulation of these dimensional errors becomes large, and the radial position of the air gap G portion and the coil 31 cannot be obtained with sufficient accuracy. There is a problem that the drive displacement of the magnetic head 12 cannot be obtained with high accuracy.

The present invention has been made in order to solve such a problem, and the number of parts of the magnetic head drive unit is reduced, the assembling is easy, the size and weight are reduced, and the dimensional error due to the components is integrated. It is an object of the present invention to obtain a magnetic recording / reproducing apparatus in which the dimensional accuracy of the air gap is improved and the accuracy of driving displacement of the magnetic head is improved.

[0011]

In a magnetic recording / reproducing apparatus according to the present invention, a leaf spring is supported between an upper yoke and a lower yoke as a magnetic head driving portion, and a magnetic field is applied to a tip of an extending portion extended from the leaf spring. The head is attached. A coil or permanent magnet is fixed to the leaf spring, and a permanent magnet (when the coil is fixed to the leaf spring) or an air-core or iron-core coil (when the permanent magnet is fixed to the leaf spring) is axially opposed to the leaf spring. The yoke is fixed to at least one of the two yokes.

[0012]

In the present invention, a magnetic flux is generated by supplying a drive current to the coil of the magnetic head drive section, and an attractive force or a repulsive force acts between the magnetic flux generated by the permanent magnet or the opposing coil to cause the leaf spring to move. The magnetic head is vertically driven and displaced. The magnetic head driving unit has a simple structure and is easy to assemble.

[0013]

1 is a longitudinal sectional view of an embodiment of a magnetic head drive section of a magnetic recording / reproducing apparatus according to the present invention. Reference numeral 40 is a magnetic head drive unit, 41 is a lower yoke made of a non-magnetic material, 42 is an upper yoke made of a non-magnetic material fixed to the lower yoke 41, and mounting screw holes 42b are formed. 43 is a leaf spring made of a non-magnetic material and fixed by sandwiching the outer circumferential side between the yokes 41 and 42.It has a plurality of radial slits to increase elasticity and extends from the inner circumferential side. Existing part 43a is a window hole 4
A magnetic head 12 is attached to the tip of the magnetic head 12 so as to project through 1a and 42a. Reference numeral 44 denotes a cylindrical first permanent magnet fixed to the yoke 42, 45 denotes a cylindrical second permanent magnet fixed to the yoke 43 and axially opposed to the permanent magnet 44 through the air gap G _1. Is a hollow cylindrical coil fixed to the inner circumferential side of the leaf spring 43.

The operation of the magnetic head drive section 40 will be described with reference to FIG. The N poles of the permanent magnets 44 and 45 face each other,
Both magnetic fluxes are repelling. When an electric current is applied to the coil 46 in the direction shown in the drawing, a magnetic flux is generated, and the coil 46 exerts an attractive force on the permanent magnet 45 side and a repulsive force on the permanent magnet 44 side. As a result, the magnetic head 12 moves upward via the leaf spring 43. When the coil current is reversed, the magnetic head 12 moves downward from the neutral position.

FIG. 3A is a vertical sectional view of a magnetic head drive section according to the second embodiment of the present invention. Magnetic head drive
48 does not include the first permanent magnet 44 of FIG. Although the drive sensitivity of the magnetic head 12 is slightly lowered, the height of the magnetic head drive section 48 can be made lower.

FIG. 3B shows a magnetic head drive unit according to the third embodiment of the present invention. The magnetic head drive unit 49 has an air-core cylindrical coil 50 fixed to the yoke 42, and a short columnar permanent magnet 51 fixed to the inner circumferential side of the leaf spring 43 so as to face each other with a gap in the axial direction. .

FIG. 4 shows a magnetic head drive unit according to the fourth embodiment of the present invention. The magnetic head drive unit 53 fixes the upper yoke 42 and the intermediate yoke 54, and holds the outer circumferential side of the leaf spring 43 therebetween. 54a is a window hole. Middle yoke 5
4 and the lower yoke 41 are fixed to each other, and an auxiliary leaf spring 55 is sandwiched between them. A permanent magnet 45 is fixed to the yoke 42, and a leaf spring 43
A hollow cylindrical coil 46 is fixed to the inner circumferential side of and is opposed to each other through a gap in the axial direction. The inner peripheral side of the leaf spring 43 and the inner peripheral side of the auxiliary leaf spring 55 are connected by a connecting member 56. With this configuration, it is possible to absorb disturbance in the protruding direction of the magnetic head 12.

Although the yokes 41, 42 and 54 are made of a non-magnetic material in the above embodiment, they may be made of a magnetic material and the driving sensitivity of the magnetic head 12 is further improved.

Next, each embodiment of the magnetic head drive section according to another means of the present invention will be described. FIG. 5A shows a fifth embodiment. The magnetic head drive unit 60 is configured as follows. The lower yoke 61 and the upper yoke 62 made of a magnetic material are fixed to each other, and the leaf spring 43 is sandwiched between them on the outer circumferential side,
The magnetic head 12 is attached to the tip of the extending portion 43a from the inner circumferential side of the leaf spring 43. 61a and 62a are window holes, 62b is a mounting screw hole, 63 is an iron core attached to the yoke 62, 64 is a cylindrical coil wound around this iron core, and 65 is an inner circumferential side of the leaf spring 43. It is a fixed short cylindrical permanent magnet with an iron core 63
Are opposed to each other in the axial direction via an air gap G ₂ . With such a configuration, the magnetic head drive unit 60 has a small number of parts, is easy to assemble, is inexpensive, and is small and lightweight. FIG. 5B shows a plan view of the leaf spring 43. The leaf spring 43 is provided with a plurality of circumferential slits 43b to impart elasticity. A radially extending portion 43a is provided from the inner circumference side.

The operation of the magnetic head drive unit 60 will be described with reference to FIG. When the coil 64 is energized in the direction
A magnetic flux F is generated in the closed magnetic circuit by the 63 and the yokes 62, 61. This magnetic flux F is in the same direction as the magnetic flux of the permanent magnet 65, and the permanent magnet 65 is attracted upward by the attractive force. As a result, the magnetic head 12 is moved upward via the leaf spring 43.

Further, in order to move the magnetic head 12 downward, it is adjusted by fixing the permanent magnet 65 in an arrangement in which the polarities are reversed, or by changing the current direction of the coil 64.

FIG. 5C shows the sixth embodiment. The magnetic head drive unit 60 is different from the fifth embodiment in that an iron core 66 is used.
Is the shape of. The iron core 66 is provided with brim portions 66a and 66b for holding the coil 64 up and down so that the coil 64 can be easily wound in a correct position. The rotating cylinder 6 (see Fig. 9) rotates at high speed and easily vibrates, but the coil 64 has an iron core.
It is held by the flanges 66a and 66b on the 66, and is prevented from shifting up and down to improve reliability.

FIG. 6A shows a seventh embodiment. The magnetic head drive unit 67 has an iron core 68 fixed to the lower yoke 61 and opposed to the permanent magnet 60 in the axial direction with an air gap G ₃ interposed between the magnetic head drive unit 67 and the fifth embodiment shown in FIG. 5A. A cylindrical coil 69 is wound around the iron core 68. By passing a current through the coils 64, 69 in the direction shown in the figure, the permanent magnet 65 receives an attractive force from the iron core 63 and a repulsive force from the iron core 68, and a large amount of displacement of the magnetic head 12 can be obtained in the upward direction, further downsizing. it can.

The eighth embodiment is shown in FIG. 6B, and the shapes of the upper and lower iron cores differ from the seventh embodiment of FIG. 6A. The upper iron core 66 is provided with flanges 66a and 66b to facilitate the winding of the coil 64 and ensure the holding. Also, the lower iron core
The ribs 70a and 70b are provided on the 70 to facilitate the winding of the coil 69 and ensure the holding.

FIG. 7A shows a ninth embodiment. The magnetic head drive unit 71 has an air-core coil 72 fixed to the leaf spring 43 instead of the permanent magnet 65 shown in FIG. Coils 64, 6
When a drive current is applied to 9, 72 in the direction shown, the magnetic head 12
Can be driven in the axial direction. In this case, Fig. 6 (A)
The leakage of the magnetic field by the coil 72 is less than the leakage of the magnetic field which the permanent magnet 65 always gives to the magnetic head 12 at.
As a result, a good signal with less noise can be recorded and reproduced. Further, when there is no problem even if the resonance frequency is lowered to some extent, by inserting an iron core in the air-core portion of the coil 72, the magnetic permeability can be increased and a larger displacement amount of the magnetic head 12 can be obtained. In this case, the shape of the iron core of the air core is not limited.

FIG. 7B shows a tenth embodiment. The magnetic head drive unit 74 fixes the iron core 75 to the leaf spring 43, and winds the coil 72 between the flange portions 75a and 75b of the iron core to facilitate the positioning and hold it so as not to vertically shift. A coil 64 is wound around the iron core 66 between the brim portions 66a and 66b, and a coil 69 is wound around the iron core 70 between the brim portions 70a and 70b and held respectively.

FIG. 8 shows an eleventh embodiment. The magnetic head drive unit 76 uses an iron piece 77 instead of the coil 72 of FIG.
It sticks to 3. In this case, by passing a current through one of the upper and lower coils 64, 69, the iron core of the coil serves as an electromagnet, the iron piece 77 is attracted, and the magnetic head 12 is driven and displaced through the leaf spring 43. In this case, since only the attractive force is used, the displacement amount is somewhat small, but the manufacturing price is low because no permanent magnet is used.

The iron cores 63, 68,
The shapes, numbers, forming positions, etc. of the coils 46, 50, 64, 69, 72 and the iron piece 77 may be appropriately changed as long as the magnetic head 12 can be driven and displaced.

[0029]

As described above, according to the present invention, as the magnetic head driving unit, the leaf spring is sandwiched between the upper yoke and the lower yoke, and the magnetic head is provided at the tip of the extending portion of the leaf spring. Attach the coil or permanent magnet to the leaf spring, and attach the permanent magnet (when the coil is fixed to the leaf spring) or coil (when the permanent magnet is fixed to the leaf spring) axially facing the coil or permanent magnet to the leaf spring. The magnetic head drive unit is fixed to at least one of the upper and lower yokes, and the drive current is passed through the coil to drive and displace the magnetic head in the vertical direction via the leaf spring. The number of parts is reduced, the configuration is simple, the assembly is easy, the productivity is improved, and the cost is reduced. In addition, the size and weight are reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a magnetic head drive unit of a magnetic recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the magnetic head drive unit of FIG.

FIGS. 3A and 3B are vertical cross-sectional views of a magnetic head drive unit showing second and third embodiments of the present invention.

FIG. 4 is a vertical cross-sectional view of a magnetic head drive portion showing a fourth embodiment of the present invention.

5A is a vertical cross-sectional view of a magnetic head drive unit showing a fifth embodiment of the present invention, FIG. 5B is a plan view of the leaf spring shown in FIG. 5A,
FIG. 6C is a vertical sectional view of a magnetic head drive portion showing a sixth embodiment of the present invention.

6A and 6B are longitudinal sectional views of a magnetic head driving portion showing the seventh and eighth embodiments of the present invention.

7 (A) and 7 (B) are vertical sectional views of a magnetic head driving section showing the ninth and tenth embodiments of the present invention.

FIG. 8 is a vertical cross-sectional view of a magnetic head drive portion showing an eleventh embodiment of the present invention.

9A is a vertical sectional view of a rotary head assembly of a conventional magnetic recording / reproducing apparatus, and FIG. 9B is a sectional view taken along line B ₉ -B ₉ of FIG. 9A.

10A is a plan view of the magnetic head driving unit of FIG. 9A, FIG. 10B is a sectional view taken along line B ₁₀ -B ₁₀ of FIG. 10A, and FIG.
The figure is a side view of FIG.

11 is a diagram showing a magnetic recording trace of a magnetic tape by the magnetic head driving unit of FIG.

FIG. 12 is a vertical cross-sectional view of a magnetic head drive unit showing another example of the related art.

[Explanation of symbols]

1 magnetic tape 6 rotating cylinders 12 magnetic head 40 Magnetic head drive 41 Upper yoke 42 Lower yoke 43 leaf spring 43a extension 44, 45 permanent magnet 46 coils 48, 49, 53, 60, 67, 71, 74, 76 Magnetic head drive 51, 65 Permanent magnet 50, 64, 69, 72 coils 55 Auxiliary leaf spring 56 Connection member 63, 66, 68, 70, 75 Iron core 77 Iron piece

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kimihide Nakatsu             Nagaokakyo Baba Institute 1 Mitsubishi Electric Stock Association             Company Electronic Product Development Laboratory

Claims (7)

[Claims] 1. A magnetic head drive unit is mounted in a rotary cylinder, a magnetic head is ejected from the magnetic head drive unit, and the magnetic tape running along the outer circumferential surface of the rotary cylinder is provided with the magnetic tape. In a magnetic recording / reproducing apparatus in which a magnetic head is contacted from the inside, an upper yoke and a lower yoke are sandwiched between these yokes, and an extending portion is passed through both yokes in a radial direction to extend the magnetic field at the tip. A leaf spring to which the head is attached, an air-core coil fixed to the leaf spring, and at least one of the two yokes are fixed, and the magnetic pole surface faces the coil through a gap in the axial direction. By providing a magnetic head drive unit composed of a permanent magnet and energizing the coil,
A magnetic recording / reproducing apparatus in which the magnetic head is vertically displaced via the leaf spring. 2. A leaf spring is sandwiched between an upper yoke and an intermediate yoke, an auxiliary spring is sandwiched between the intermediate yoke and a lower yoke, and the leaf spring and the auxiliary spring are connected by a connecting member. The magnetic recording / reproducing apparatus according to claim 1, wherein a permanent magnet is fixed to the upper yoke. 3. A magnetic head drive unit is mounted in the rotary cylinder, the magnetic head is ejected from the magnetic head drive unit, and the magnetic tape running along the outer circumferential surface of the rotary cylinder is attached to the magnetic tape. In a magnetic recording / reproducing apparatus in which a magnetic head is contacted from the inside, an upper yoke and a lower yoke are sandwiched between these yokes, and an extending portion is passed through both yokes in a radial direction to extend the magnetic field at the tip. A leaf spring to which the head is attached, a permanent magnet fixed to the leaf spring, and at least one of the two yokes are fixed to each other and face the magnetic pole surface of the permanent magnet with a gap in the axial direction. A magnetic head drive unit provided with an air-core coil is provided, and by energizing the coil, the upper magnetic head is vertically displaced via the leaf spring. Magnetic recording / reproducing device. 4. The magnetic recording according to claim 3, wherein an iron core is inserted into the air-core portion of the coil and fixed to the yoke, and the pole surface is axially opposed to the magnetic pole surface of the permanent magnet through an air gap. Playback device. 5. A magnetic head drive unit is mounted in a rotary cylinder, and a magnetic head is ejected from the magnetic head drive unit, and the magnetic tape running along the outer circumferential surface of the rotary cylinder is attached to the magnetic tape. In a magnetic recording / reproducing apparatus in which a magnetic head is contacted from the inside, an upper yoke and a lower yoke are sandwiched between these yokes, and an extending portion is passed through both yokes in a radial direction to extend the magnetic field at the tip. A leaf spring to which a head is attached, an air-core coil fixed to the leaf spring, and a pair of upper and lower iron cores fixed to the both yokes and having pole faces axially opposed to the coil via a gap. , A magnetic head drive unit provided with a coil wound around each of these iron cores, and by energizing each of the coils, the magnetic head is vertically moved through the leaf spring. A magnetic recording and reproducing device that is configured to be displaced. 6. An iron core is inserted into an air-core portion of a coil on the leaf spring and fixed to the leaf spring, and upper and lower pole faces are axially opposed to the pole faces of the upper and lower iron cores, respectively. Item 5
The magnetic recording / reproducing apparatus described. 7. An iron piece is fixed in place of the coil on the leaf spring, and the upper and lower surfaces of the iron piece are opposed to the pole faces of the upper and lower iron cores, respectively, in the axial direction via air gaps. The magnetic recording / reproducing apparatus according to claim 5.